A GLOSSARY FOR COLOR AERIAL RECONNAISSANCE

• Document Type: CREST
• Collection: NGA Records (Formerly NIMA)
• Document Number (FOIA) /ESDN (CREST): CIA-RDP78B04560A007300010028-8
• Release Decision: RIFPUB
• Original Classification: C
• Document Page Count: 167
• Document Creation Date: December 28, 2016
• Document Release Date: March 25, 2003
• Sequence Number: 28
• Publication Date: January 1, 1972
• Content Type: REPORT

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TECHNICAL
PUBLICATION
NATIONAL PHOTOGRAPHIC
INTERPRETATION CENTER
A GLOSSARY FOR
COLOR AERIAL RECONNAISSANCE
Declass Review by NIMA / DoD
GROUP 1: EXCLUDED FROM
AUTOMATIC DOWNGRADING
AND DECLASSIFICATION
CONFIDENTIAL
NPIC/R-01/72
JANUARY 1972
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This document contains information affecting
the national defense of the United States,
within the meaning of Title 18, sections
793 and 794, of the U.S. Code, as amended.
Its transmission or revelation of its contents
to or receipt by an unauthorized person is
prohibited by law.
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CONFIDENTIAL NPIC/R-01/72
A GLOSSARY FOR
COLOR AERIAL RECONNAISSANCE
January 1972
NATIONAL PHOTOGRAPHIC INTERPRETATION CENTER
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CONFIDENTIAL NPIC/R-01/72
TABLE OF CONTENTS
Page
1.0 INTRODUCTION . . . . . . . . . . . . . . . . . . .
2.0 GLOSSARY . . . . . . . . . . . . . . . . . . . . .
154
3.0 APPENDIX . . . . . . . . . . . . . . . . . . . .
161
4.0 REFERENCES . . . . ? ? ? ? ? ? ? ? ? ? ' ' ' '
, 155
FIGURE 1 HORIZONTAL SECTION OF THE EYE . . . . . . . . . .
156
FIGURE 2 CHROMATICITY DIAGRAM . . .
FIGURE 3 DSPECTRAL IFFERENT EDIRECTIONS RAANDT UNDER DIFFERENT CONDITIONS
AT CLEVELAND, OHIO . . . . . . . . . . . . . . . . . . . 15 7
FIGURE 4 LIGHT UNITS . ? ? ? ? ? ? ? ? ? ? ' ' ' ' ' 158
LIST OF TABLES
159
TABLE 1 CONVERSION TABLE . . . . . . . . . . . . . .
TABLE 2 SUMMARY OF THE BETTER KNOWN COLOR VISION THEORIES . . . 160
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This glossary attempts to define and describe in simple, under-
standable language a set of words, concepts, and measures related to color
aerial reconnaissance. The purpose of the glossary is to provide a
reference which can be used to learn and understand basic terminology
related to color-aerial reconnaissance and to help improve communication
'concerning color. For maximum usefulness several criteria were used to
guide and limit the compilation and writing of the glossary:
1. The words chosen and their definitions should be
relevant to color as it relates to aerial
reconnaissance. Since aerial reconnaissance is
broad, the Glossary is broad, covering terminology
from color aerial photography (its acquisition,
processing, and interpretation), and from the
psychology, physiology, physics, and measurement
of color. Yet within these broad categories
there are gaps in terminology which are not
related to aerial reconnaissance. Thus the reader
should not expect to find a complete and
comprehensive glossary on Color.
2. The language (terms and concepts) of the glossary
should be easy to understand so that a wide range
of personnel in aerial reconnaissance could read
and understand the material included. For those
who wish or need to know greater technical detail,
theory, or procedures there are a number of
excellent references in all technical areas.
3. Extraneous words and concepts should be omitted
so that the material can be presented in a succinct
manner.
To help satisfy these criteria, a review of the major literature
in aerial reconnaissance and in related technical fields was performed and
major sources, e.g., technical textbooks, manuals, glossaries, and
dictionaries were selected for use. These sources were then searched for
relevant words, concepts, and measures, resulting in over 1,000 terms to
be included. Each term had at least two or three definitions, so the
most appropriate one had to be chosen. Then, if necessary, it had to be
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rewritten in order to adhere to the prescribed format (discussed below).
In addition, figures, tables, and added explanations in the form of "Notes",
were used to help clarify the definitions and aid in reader understanding.
Important aspects of the Format are enumerated below:
(1) The terms are arranged in alphabetical order and
are capitalized. Following certain terms one or
more synonyms will appear in parentheses.
Reference numbers in brackets also will be used
if the definition has been taken from the source,
either verbatim or slightly modified.
(2) Under each term is the definition, and if more
than one definition is used, they are enumerated.
Within a definition, important words, if also
defined in the glossary, are capitalized.
(3) Following the definition(s) there may be a "Note"
which is used for additional explanation and
illustration.
(4) Finally, a "See Also" is used when the reader
should refer to another glossary word for further
explanation.
All major figures and tables are found in the Appendix and a
general reference list is included which contains the major sources for the
glossary.
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ABAXIAL [4]
2.0 GLOSSARY
A
ABERRATION [12]
A ray of light that does not
coincide with the OPTICAL AXIS.
A marginal ray passing through a
lens.
Note: See Figure below, light
ray x is ABAXIAL.
ABBE NUMBER [8]
The number expressing the extent
to which the shorter and longer
wavelengths of light are separated
by refraction through a particular
The failure of an optical system
to bring all light rays received
from a point object to a single
image.
Note: Defects in the performance
of a lens or mirror which prevent
it from giving an absolutely
sharp image. In practice the
complete removal of all aberra-
tions is impossible. The aberra-
tions inherent in any optical
system are listed below.
See Also: CHROMATIC ABERRATION;
SPHERICAL ABERRATION; COMA;
CURVATURE OF FIELD; ASTIGMATISM;
and DISTORTION
glass, i.e., the amount the glass ABNEY EFFECT
disperses the various colors. The
greater the number, the smaller
the dispersion, i.e., the less
the separation of the colors
after refraction. In practice
they vary from about 25.5 for
Double Extra Dense Flint glass
to 60.3 for Hard Crown glass.
Note: The Abbe Number is (nD-1)/
(nF-nc) where n is refractive
index and the subscripts indicate
measurement at the sodium D line
(589 nm), the hydrogen F line
(486 nm), and the hydrogen C line
(656 nm).
The change in apparent HUE which
may occur when SATURATION is
changed.
A compromise to true SPECTRO-
PHOTOMETRY in which a set
(often 10-16) of narrow-bandpass
filters (5-20-nm half width)
is used to provide an approxima-
tion to the complete spectrophoto-
metric curve.
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ABSOLUTE TEMPERATURE [4]
A temperature with the Kelvin (K)
scale, having degrees the same
size as Celsius (Centigrade) and
zero placed at approximately
-273 C. Thus 0 C. = 273 K.
100 C.= 373 K.
ABSORBANCE, SPECTRAL
Absorbance at a specified wave-
length.
ABSORBANCE [5] (ABSORPTION FACTOR)
Logarithm (to the base 10) of
the ratio of the light (LUMINOUS
FLUX) incident on a transparent
body, to that emerging from it.
Preferred to DENSITY or OPTICAL
DENSITY.
Light which is converted into
heat when passing through a body.
ABSORPTION (SELECTIVE ABSORPTION)
The dissipation of light into
heat when passing through a
medium. The remaining light
is either TRANSMITTED or
REFLECTED.
Note: Color of objects is the
result of selective absorption
of certain wavelengths. If
white light falls on a surface
that absorbs the red and green
rays, the surface appears blue
to the eye because that is the
only visible light reflected by
the surface. If white light
passes through a transparency
that absorbs all wavelengths but
red, the transparency will be
perceived as red.
ABSORPTION BAND (ABSORPTION LINE) [4]
The dark band or line in the
spectrum or SPECTROGRAM caused
by the failure of the material
that is being analyzed to
transmit light of that wave-
length.
Note: For example, a yellow
filter will not transmit a
certain portion of wavelengths
in the blue region. The SPECTRO-
GRAM of the yellow filter would
show dark lines at those wave-
lengths.
ABSORPTION COEFFICIENT
See ATTENUATION COEFFICIENT
ABSORPTION CURVE 18]
Graphic representation of the
ABSORBANCE of a medium, plotted
against the wavelength of the
light. Generally used to give
an indication of the characteris-
tics of color filters and dyes
in color films.
Note: The Figure below is an
Absorption Curve for a yellow
filter (minus-blue filter).
500 600 700
Wavelength, nm
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ABSORPTION FACTOR
See ABSORBANCE
ACCELERATOR
A term often applied to the
alkaline constituent of a
developing solution because
increasing the amount of alkali
in all normal cases speeds up
the action of a developer.
(1) The
faculty
of the human eye
(lens) to
adjust
(focus) in order
to render
sharp
images for
different
object
distances (4 to
5 inches to infinity).
(2) The ability of the eyes to
bring two images into superimposi-
tion for stereoscopic viewing.
(1) Lacking in HUE and SATURATION,
and varying only in BRIGHTNESS, or
LIGHTNESS, e.g., black, white, or
any gray.
(2) When applied to a lens, it
means that the lens has been
corrected for CHROMATIC ABERRATION
at two wavelengths.
See Also: ACHROMATIC LENS
ACHROMATIC COLOR [5]
Color perceived to have no HUE.
Note: Examples of Achromatic
Color are black, gray, white,
and "clear, colorless".
ACHROMATIC LENS (ACHROMAT) [4]
A lens that is corrected for
chromatic aberration at two wave-
lengths of light. A lens that is
customarily made to bring green
and red light rays to approximately
the same point focus.
Note: Such a lens is not suffi-
ciently corrected for color
photography, ADDITIVE COLOR
SEPARATIONS, or COLOR SEPARATION
NEGATIVES
See Also: APOCHROMATIC LENS
ACHROMATIC LIGHT [5]
Light perceived as having no HUE.
ACHROMATIC OBJECT [11]
An object that reflects or transmits
the same proportion of light at
each wavelength. Thus, appearing
ACHROMATIC, e.g., black, white,
or grays.
ACHROMATIC POINT [5]
Point in the CHROMATICITY DIAGRAM
in the CIE color system used as
the basis for determination of
DOMINANT and COMPLEMENTARY WAVE-
LENGTHS and for EXCITATION PURITY
because it represents the
CHROMATICITY of a color which is
acceptable as achromatic under
the conditions in which the colors
are observed. Usually, the
chromaticity of the illuminant
is used for this point.
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ACHROMATIC POINT [5] (Continued)
Note: See Figure 2 in the
Appendix. The center of the
circle denoted as "WHITE" is
the Achromatic Point.
ACHROMATIC REGION [5]
The part of a CHROMATICITY DIAGRAM
in the CIE Color System that rep-
resents ACHROMATIC COLORS under
circumstances of common occurrence.
Note: See Figure 2 in the
Appendix. The area inside the
circle denoted as "WHITE" is the
Achromatic Region.
ACHROMATOPIA (ACHROMATOPSIA,
ACHROMATISM) [5]
Type of MONOCHROMATISM in which
all colors are perceived as
achromatic or total color blind-
ness.
ACTINIC LIGHT [4]
ACUITY, VISUAL [4]
A measure of the eye's ability to
separate details in viewing an
object. The reciprocal of the
minimum angular separation, in
minutes of arc, of two lines of
detail which can be seen separately.
ACUTANCE [4]
A complex, objective measure of
the ability of a photographic
system to show a sharp edge
between continuous (touching)
areas of low and high.
The degree of sharpness and con-
trast of edges in an image.
The faculty of the human eye to
adjust its sensitivity to varying
intensities and colors of illumina-
tion.
A part of the spectrum (usually
infrared, visible, and ultra- See Also: ADAPTATION, DARK;
violet wavelengths) that causes ADAPTATION, LIGHT; AND ADAPTATION,
chemical changes to occur CHROMATIC
in light sensitive photographic
emulsions. The light that creates ADAPTATION, CHROMATIC
images on light sensitive material.
The blue or violet portion of the The faculty of the human eye to
spectrum would be the actinic band adjust its sensitivity to
of light for blue or violet differences in HUE and SATURATION,
sensitive photographic materials. or colors.
ACTINOMETER [4]
An instrument for measuring the
ACTINIC value of light according
to a given scale.
Note: When staring at a single
color, the eye adapts to it;
but upon looking at another
color, the eye must adapt again
before the color will be perceived
optimally.
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ADAPTATION, CHROMATIC (Continued)
However, this adaptation occurs
relatively quickly.
ADAPTATION, DARK
The faculty of the human eye to
increase its sensitivity to
reduced illumination.
Note: In total darkness, dark
adaptation takes 30 to 45 minutes,
although-in 15 minutes sensitivity
has increased significantly.
ADAPTATION, LIGHT
The faculty of the human eye to
lower its sensitivity to
increased illumination.
Note: Light adaptation occurs in
a few minutes.
A COLOR MATCHING procedure in which
the standard is varied by adding
various proportions of different
colors.
See Also: THREE-COLOR MIXTURE;
NEGATIVE COMPONENT IN COLOR
MIXTURE
The principle that most colors can
be formed by mixing the lights of
two or more other colors.
A method for reproducing all colors
using the principle of ADDITIVE
SYNTHESIS. Usually, black-and-white
positive transparencies are
acquired through the primary color
filters (blue, green, and red), and
are projected and viewed in
register by means of light beams
of the same primary colors.
ADDITIVE SYNTHESIS (ADDITIVE COLOR
MIXTURE) 151
The formation of a color by mixing
light of two or more other colors.
Most colors may be formed by mixing
light of three conveniently select-
ed primary colors (blue, green, and
red) in the proper proportions.
Some colors may be formed by
mixing light of two colors.
Note: For example, a mixture of
blue and green lights produces CYAN,
a mixture of blue and red lights
produces MAGENTA, and a mixture of
green and red lights produces
YELLOW.
See Also: NEGATIVE COMPONENT IN
COLOR MIXTURE
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ADJACENCY EFFECTS AERIAL EXPOSURE INDEX (A.E.I) [4]
When two adjacent areas of an
image receive exposures of
different magnitude, their
respective densities and the
position of their common boundary
may not reflect the exact distribu-
tion of light within the emulsion
at the time of exposure. The
results are known as Adjacency
The reciprocal of twice the
exposure, expressed in meter-
candle-seconds, at the point of
the TOE of the CHARACTERISTIC
CURVE where the slope equals
0.6 gamma when recommended
processing and exposure conditions
are used.
Effects. In color materials, AFFECTIVE COMBINATION, LAW OF [6]
during processing, the DEVELOPMENT
products may diffuse away from
the
silver halide grains and react
with
the-DYE COUPLER to form a
dye
image
at some distance from
the
silver
image. The secondary
dye
image
improves edge definition,
but also produces objectionable
halos. Color fringing may also
occur as a result of unequal
effects in the several dye layers.
ADVANCING COLORS [5]
There are WARM COLORS (typically
reds) which are perceived, or tend
to be perceived, leaving the
picture plane or physical plane
and approaching nearer to the
observer.
Note: When viewing color
transparencies or prints, the
objects imaged as "warm colors"
may appear to stand out from the
image. During stereo viewing
this may cause exaggerated
heights.
The "pleasantness" value of a
combination of colors is highly
dependent on the "pleasantness"
of the component colors. This
law holds for CHROMATIC as well
as ACHROMATIC colors.
AFTER-IMAGE (AFTER-SENSATION)
A visual sensation occurring after
stimulation has ceased which was
caused by and appears as the
previous stimulation.
Note: Staring at a target on film
for many seconds (time varies
between individuals) can cause
an after-image of that target and
interfere with subsequent viewing.
See Also: AFTER-IMAGE, NEGATIVE;
AFTER-IMAGE, POSITIVE; AFTER-
IMAGE, PURKINJE
AFTER-IMAGE, HERING [5]
The first POSITIVE AFTER-IMAGE
which occurs following a brief
light stimulus.
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AFTER-IMAGE, NEGATIVE (COMPLEMENTARY this image is never simply a point,
AFTER-IMAGE) but a small disk, no matter how
perfect the lens.
A visual after-image in which black
and white shades are reversed and AIRY RINGS
the colors are usually approx-
imately COMPLEMENTARY to those The rings (or diffraction patterns)
of the original response. surrounding the AIRY DISK caused
by the DIFFRACTION characteristics
AFTER-IMAGE, POSITIVE (HOMOCHROMATIC of the optical system.
AFTER-IMAGE)
A visual after-image in which black
and white shades are the same and The ratio of reflected-to-
the colors are approximately the incident light.
same as those of the original
response. Note: This ratio for any one
surface is independent of the
AFTER-IMAGE, PURKINJE intensity of light source.
A visual after-image in which black ALCOHOL, ABSOLUTE
and white shades are the same and
the colors are approximately Chemically pure ethyl alcohol
COMPLEMENTARY to those of the without water.
original response.
Ag.
Chemical symbol for silver.
AGITATION [4]
ALCOHOL, DENATURED
Ethyl alcohol rendered unfit
for drinking by the addition of
agents known as denaturants.
Almost all industrial alcohol
is denatured.
The process of circulating the
photographic solution in which the ALCOHOL, METHYLATED
film or paper is immersed. To
bring fresh solutions into contact English term for one kind of
with the emulsion. Bubbling denatured alcohol.
nitrogen through the solutions is
a commonly used method of agita- ALTITUDE
tion.
AIRY DISK [4]
Vertical distance of an object
or point above DATUM, usually
mean-sea-level.
The image of an infinitely distant
point as focused on a plane by a
diffraction limited lens. Because
of the wave structure of light,
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ALYCHNE
The line or locus of points on the
CIE CHROMATICITY DIAGRAM that
corresponds to the CHROMATICITY
COORDINATES of the normal colors
that have zero luminosity. By
locating two of the three CIE
PRIMARIES at the extremes of the
alychne the CIE Committee made the
CIE y color-matching function
identical with the PHOTOPIC CURVE
of the STANDARD OBSERVER. This was
done to facilitate the computation
of photometric quantities from
color matching data.
Loss of sight due to defect of the
optic nerve which is not
accompanied by any perceptible
change in the eye itself.
Dimness of vision for which no
organic defect in the refractive
system of the eye has been
discovered.
Note: Found in total color-
blindness, in albinism, in toxic
conditions, and is associated with
the excessive use of drugs.
AMERICAN NATIONAL STANDARDS INSTITUTE
See ANSI
Old name for what is now the
American National Standards
Institute. See ANSI.
A stereogram in which the two views
are printed or projected super-
imposed in complementary colors,
usually red and green. By viewing
through filter spectacles of
corresponding COMPLEMENTARY colors,
a stereoscopic image can be viewed.
Analogous colors are those which
have some perceptible similarity
or close relationship with respect
to one or more of the attributes
of color; as, closely related in
HUE, or BRIGHTNESS, or SATURATION.
Note: Usually the term refers
to the relation of hues alone; as,
reds and oranges or greens and
yellow-greens are called Analogous
hues or colors.
ANALYTICAL DENSITOMETRY (ANALYTICAL
DENSITIES)
A means of determining the amounts
of the individual colorants (CYAN,
MAGENTA, and YELLOW dyes) in an
element of a photographic image.
Note: There are three types of
Analytical Densities (see also):
ANALYTICAL SPECTRAL DENSITY;
EQUIVALENT NEUTRAL DENSITY; and
EQUIVALENT NEUTRAL PRINTING
DENSITY.
ANALYTICAL SPECTRAL DENSITY (ASD)
The density of a single dye or
colorant at a single wavelength.
Note: In color films, it is a
measure of the amount of dye
deposit in a dye layer.
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A lens which does not magnify
equally along mutually perpendic-
ular axes.
A lens which has been corrected
for ASTIGMATISM.
ANASTIGMATIC LENS [4]
See ANASTIGMAT
ANGLE
The difference in direction between
two intersecting lines.
Note: The unit measures of an
angle are the Degree (the 1/360
part of a circle) or the Radian
(the angle resulting when the
length of an arc is equal to its
radius). 1 Radian = 57? 17' 44".
ANGLE OF COVERAGE [4]
The apex angle of the cone of
rays passing through the front
NODAL POINT of a lens. Lenses
generally are classified according
to their angles of coverages, as
follows:
narrow-angle
-- Less than 60?
normal-angle
--
60? to 75?
wide-angle
--
750 to 1000
super-wide angle or ultra-wide
angle -- Greater than 1000
0
ANGSTROM UNIT (A) [4]
An old unit of measure for the
wavelength of light, equal to one
'tenth of a manometer: for example,
the visibleospectrum gxtends from
about 4,000A to 7,000A (400 to 700
nanometers) .
An apparatus for determining
color deficiencies in human
vision.
ANOMALOUS TRICHROMATIC VISION
(ANOMALOUS TRICHROMATISM) [5]
A form of defective color vision
in which three primaries are
required for color matching, but
the proportions in which they are
matched differ significantly from
those required by the NORMAL
TRICHROMAT.
Note: Generally these people can
see all colors but are weak in a
particular color. There are
three forms of Anomalous
Trichromatism -- PROTANOMALOUS,
DEUTERANOMALOUS, and TRITANOMALOUS
VISION. They cover the ranges of
defective color vision lying
between normal trichromatism and
complete PROTANOPIA, DEUTERANOPIA,
or TRITANOPIA, respectively.
See Also: PROTANOMALOUS VISION;
DEUTERANOMALOUS VISION;
TRITONOMALOUS VISION
American National Standards
Institute, formerly United States
of America Standards Institute
(USASI), and before that American
Standards Association (ASA).
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ANSI (Continued)
Because of widespread usage, some
ANSI standards retain the designa-
tion ASA as in ASA speed.
ANTI-FOGGING AGENT (ANTIFOGGANTS;
FOG RESTRAINERS)
Chemical included in a DEVELOPER
or EMULSION to retard the forma-
tion of development FOG.
ANTI-HALATION BACKING [4]
A light-'absorbing coating applied
to the back side of the support
of a film or plate (or between
the EMULSION and the SUPPORT) to
suppress HALATION.
Very thin coating of a metallic
fluoride applied to a glass
surface -- e.g., of a lens -- to
reduce light lost by reflection.
The most commonly used anti-
reflection-film material is
magnesium fluoride, MgF2.
Note: Color images taken without
this filter will have darkened
corners and edges. However, these
filters are often not used
because they reduce the overall
light level.
See Also: VIGNETTING
APERTURE-COLOR PERCEPTION [5]
Perception of color as filling an
aperture in a screen.
Note: An aperture-color percep-
tion is non-located in the sense
that it may be near the plane of
the screen or indefinitely far
behind it, but it tends to be
seen closer to a plane perpendic-
ular to the line of sight. It
has a filmy, soft character in
contrast to a SURFACE-COLOR
perception which has a hard
character corresponding to an
exact location in space.
See Also: FILM-COLOR
APERTURE
An opening or hole through which
light or matter can pass.
See Also: APERTURE, EFFECTIVE
A filter to correct variations
in illumination across the focal APERTURE, EFFECTIVE [4]
plane.. The rear of the filter
(over the lens) is coated with The useful area of the opening
neutral material whose DENSITY through which the ray of light
gradually decreases from the center passes to the film to produce
toward the edges to cut down the the image.
exposure of the center portion.
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APERTURE, NUMERICAL
The sine of the half angle of the
widest cone of light rays capable
of being transmitted through a
lens system, multiplied by the
INDEX OF REFRACTION of the medium
in which the object is embedded.
APERTURE STOP [4]
The physical element (such as a
stop, DIAPHRAGM, or lens
periphery) of an optical system
which limits the size of the
pencil of rays traversing the
system. The adjustment of the
size of the aperture stop of a
given system regulates the
brightness of the image without
necessarily affecting the size of
the area covered.
APERTURE, WORKING [4]
The largest DIAPHRAGM opening at
which a lens diaphragm can be set.
APOCHROMATIC LENS [4]
A lens which is corrected for
CHROMATIC ABERRATION at three
wavelengths (blue, green, and
red) of light rather than two, as
in the ACHROMATIC LENS (green
and red).
APOLSTILB (asb) (METER-LAMBERT)
A unit of LUMINANCE equivalent
to 1 candela/meter2.
Note: See Table 1 in the Appendix.
APTITUDE, COLOR
See COLOR APTITUDE
APPEARANCE PLAN
A method of developing color systems
in which the intervals on the
dimensions of colors are based on
human judgment. The MUNSELL COLOR
SYSTEM is an example.
AQUEOUS HUMOR [11]
A clear liquid (Specific Viscosity
= 1.03) which fills the chamber
between the CORNEA and the LENS.
Note: See Figure 1 in the Appendix.
Densities measured with a DENSITO-
METER whose responses do not
conform to any particular colors
or density measuring conventions.
Any combination of filters or
photo tubes may be used.
AREA EFFECT [6]
A change in color of an object
as it varies in size (independent
of distance) on the retina.
Note: As the area increases
(up to 20 degrees subtended on
the retina and under most
conditions) so does saturation.
Past 20 degrees the color becomes
progressively less saturated.
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Any illumination not produced by
the sun but which has a wide
range of wavelengths, generally
appearing white.
See Also: INCANDESCENT TUNGSTEN
LIGHT; FLUORESCENT LIGHT
ASA [ 41
American Standards Association,
now reorganized under the name
American National Standards
Institute (ANSI).
ASA (AMERICAN STANDARDS ASSOCIATION)
COLOR MEASUREMENT METHOD (Z58.71-
1951)
Commonly used method of measuring
color by spectrophotometry followed
by calculation of CIE tristimulus
values (see TRISTIMULUS VALUES,
definition 2).
ASA SPEED [8]
System of rating the speed of
sensitized materials laid down by
the American Standards Association
(now ANSI) in the ASA standards
PH2.5 -- 1960 for black-and-white
negative materials and PH2.21 --
1961 for color reversal materials.
The ASA speed for black-and-white
negative emulsions is based on
measurement of a prescribed point
of the CHARACTERISTIC CURVE which
is at a minimum density level
above base + fog density and
satisfies certain conditions of
slope. The ASA speed can be
expressed either as an arithmetical
speed -- e.g., ASA 100 -- or in a
logarithmic form where each
successive step represents a
change in sensitivity by a factor
of 2 -- e.g., ASA 5?. This form
distinguishes the ASA speed from
the older, numerically similar
exposure index figure.
With reversal color films, the
speed is based on the
CHARACTERISTIC CURVES of the
three dyes but is expressed in
the same way.
!Numerically, ASA speeds are
identical with B.S. (British
Standard) speeds as specified
by B.S. 1380: 1962.
In complex patterns, colors evoked
by small, spatially juxtaposed
areas may appear more alike than
different. When judging or naming
colors, adjacent colors may cause
perceptual errors; therefore, it
is better to isolate the colors
being judged or named.
A defect or aberration of an
optical system which results in
lines perpendicular to one
another in the object plane being
focused in different image planes.
Note: In the Figure below is an
example.
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The absorption and scattering of
light as it passes through the
atmosphere. The attenuation
affects the various wavelengths
of light differently.
See Also: RAYLEIGH SCATTERING;
MIE SCATTERING
See Also: RAYLEIGH SCATTERING;
MIE SCATTERING
Variations in the density of the
air caused by variation in
temperature and air pressure.
I = amount of light re-
maining
k = attenuation coefficient
Each material has a different
attenuation coefficient at each
wavelength.
Note: The loss can result from
scattering, absorption, or both.
When the only loss is that due to
absorption, the term Absorption
Coefficient (similarly defined)
is used.
ATTITUDE [4]
The angular orientation of a
platform or of the photograph
taken with that platform with
respect to some external reference
system. Usually expressed as PITCH,
ROLL, and YAW.
Note: Degrades high-altitude
imagery by distorting the image as ATTRIBUTES OF COLOR (DIMENSIONS OF
it passes through the atmosphere COLOR) [5]
and reduces resolution. Further-
more, atmospheric turbulence tends
to degrade the small image details
or higher spatial frequencies
more than it degrades the gross
features or lower spatial fre-
quencies in the image.
The CHROMATIC colors have the
attributes of HUE, SATURATION,
and BRIGHTNESS or LIGHTNESS, but
the ACHROMATIC colors do not have
those of hue and saturation. All
colors have the general attributes
of duration, location, and extent,
but these are rarely mentioned.
It is the proportionality constant AUBERT-FORSTER LAW [5]
that relates the amount of light
lost (EI) from a beam of light to
the amount of light (I) that
remains after the beam has
traveled a distance (Ax) in the
material, that is, AI = -kIOx
where tI = amount of light lost
Ax = distance traveled
A generalization from the Aubert-
Forster phenomenon, namely, that
VISUAL ACUITY of a near object
in the periphery is greater than
that of a similar, distant
object, even though the latter
is large enough to subtend the
same visual angle as the near
object.
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AVERAGE GRADIENT AXIS, VISUAL
A measure of contrast for a speci- An imaginary line from the object
fied portion of the CHARACTERISTIC through the NODAL POINT of the
CURVE, (slope of the line between eye to the FOVEA.
any two points on the curve).
There are no widely accepted
definitions of the two points;
therefore, they should.be specified.
Note: In the figure below, the
slopes A and B and C and D are
Average Gradients.
U)
3.0-
01
log (E)
AVOIRDUPOIS WEIGHT (AVDP) 1.4J
The system of weights in general
use in the United States. The
avoirdupois pound is defined as
453.5924277 grams. The smallest
unit of the system is the grain,
7,000 equal one pound; the next
larger unit is the dram, 256
equal one pound; the next larger
unit is the ounce, 16 equal
one pound.
AXIS, OPTICAL (PRINCIPAL AXIS) [4]
In a lens element, the straight
line which passes through the
centers of curvature of lens
surfaces. In an optical system,
the line formed by the coinciding
principal axes of the series of
optical elements (lenses).
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cu FA L
BACK FOCUS (BACK FOCAL LENGTH) [4] pressure is 760 mm of mercury or
29.92 inches of mercury at 15 C
Term used to designate the (59 F).
distance between the back surface
of a lens and the aerial image when BEAM
the camera is focused at infinity.
BAFFLE [4]
A shaft or column of light, a
bundle of rays.
Used for the absorption of stray
light within a camera or other
optical instrument.
BALANCE, COLOR
See COLOR BALANCE
BAROMETRIC ADMITTANCE [4]
The transmission of ULTRAVIOLET
LIGHT from the sun is inversely
proportional to the BAROMETRIC
PRESSURE. Thus, at high altitudes
where the pressure is low, trouble
is often experienced with the
excessive proportion of ultra-
violet light. The ultraviolet
light admittance at 29.92 inches
of mercury (sea-level) is
regarded as the standard.
Note: In high-altitude photography
UV is usually not a particular
problem since the camera faces
toward the earth and the UV has
been absorbed by the air column.
However, at oblique angles the
problem could arise.
BAROMETRIC PRESSURE [4]
The pressure of the atmosphere ex-
pressed in inches of millimeters
of mercury column height. At sea-
level, the average barometric
An optical device for dividing a
light beam into two separated beams
(e.g., a partially silvered mirror).
Usually, there must be a color
correction made because the beam
splitter may be wavelength
sensitive; thus, changing the
color of the transmitted and
reflected light.
Note: In ADDITIVE COLOR SEPARA-
TIONS the beam splitter is used
to transmit a portion of the light
to one film and reflect a portion
to another film. Selective
filters may be placed in front of
each film.
BEER'S LAW [6]
(1) Stated formally: for a
molecularly dispersed colorant
of a given thickness, the amount
of transmitted flux (It) of
single-frequency light of wave-
length X is a function of the
amount of incident flux (I0)1
the extinction coefficient (ax)
and the concentration (c) of
the medium.
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It = Ioe-a ac
(2) A mathematical expression re-
lating transmittance of a single
wavelength through a colored medium
to the INCIDENT FLUX, extinction
coefficient, and the concentration
of the medium.
BEZOLD-BRtCKE PHENOMENON
A change in hue resulting from a
change in LUMINANCE. As luminance
increases, colors which are orange
or yellow-green appear yellower
and colors which are purple or
blue-green appear bluer. The
colors of blue, green, yellow,
and red generally remain the same.
Note: If the luminance (such as
that from a light table) remains
the same during color viewing or
naming, the effect will not be a
problem.
BINOCULAR COLOR MIXTURE [5]
BINOCULAR FLICKER [5]
Flicker evoked by rapidly alternat-
ing presentation of stimuli to the
right and left eyes, usually in
such a manner that the gaps in the
stimulus presented to one eye are
filled by the stimulus presented
to the other.
BINOCULAR FUSION [5]
The combination of two images
falling upon the two retinas forming
a single visual impression. The
.images may be alike or may differ
to some degree in form and color.
Note: Stereoscopic viewing is an
example of BINOCULAR FUSION.
BINOCULAR MATCHING [1]
The matching of stimuli, such as
colors, by presenting the two
stimuli to be matched to the right
and left eyes respectively, and,
ideally, having them occupy the
two halves of a combined visual
field. To avoid BINOCULAR FUSION
The presentation of different colors of the two stimuli, fixation
to corresponding areas of the two 'points should be provided.
retinas, resulting in a single fused
impression. This effect occurs BINOCULAR RIVALRY (RETINAL RIVALRY)
only under special conditions, often
the effect is BINOCULAR RIVALRY. Alternating sensations, first
Note: During stereo viewing, if
the two images are slightly
different in color (which is
normally true due to change of
acquisition angle), the colors may
be fused or the colors will
alternate in dominance.
from one eye and then from the
other, when the two eyes are
simultaneously stimulated by
different colors or figures.
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BINOCULAR RIVALRY (RETINAL RIVALRY) BLACK
(Continued)
Note: For example, if one eye is
presented with blue and the other
red, one can get the sensation of
blue, then red, then blue, and so'
on. In stereoscopy, if the color
of one image is different from
the other, this effect can occur.
BINOCULAR VISION [5]
Vision with the two eyes operating
conjointly, usually with fixation
of both on the same objective
point.
In general, characterized by a
single perception of the objects
fixated. An important factor in
perception of space, giving
projection and depth.
See Also: MONOCULAR VISION (for
comparison)
A film consisting of two layers,
each layer sensitive to a different
portion of the SPECTRUM.
(1) Total (or near total) absence
of reflected light
(2) The ACHROMATIC COLOR of
minimum lightness or brightness.
A phrase used to denote Kodak
Infrared Aero Film 5424 which
is a negative material
of
average
resolution, sensitized
to
IR
radiation, as well as
to
the
visual spectrum. Should
be
used with a Wratten 89 B
filter
to cut out visible wavelengths.
BLACKBODY [8]
Theoretically, a perfect source
of (radiant energy) and a body
which absorbs all RADIANT ENERGY
striking it.
The conception of such a hypothet-
ical reference source is found
useful in stating the SPECTRAL
POWER DISTRIBUTION of light or
COLOR TEMPERATURE (in photog-
raphy).
Note: Most color films consist
of three layers and are called
TRIPACKS.
The first layer of nerves leading
away from the RODS and CONES
towards the front of the eye.
Activity in this layer is passed on
to the next layer, GANGLION CELLS,
at the junction called SYNAPSES.
When a solid substance is
heated, it glows first dull red,
then brighter red, and finally
white. Discounting any light
reflected from the surface, the
power distribution of the radia-
tion emitted by the substance
depends on the temperature to
which it is heated. This is
completely true for a blackbody --
i.e., one which reflects no light
falling on it.
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BLACKBODY [8] (Continued) solely by the temperature of the
radiating body.
In experimental physics such a
blackbody is obtained by cutting a BLACK CONTENT
circular opening in one side of a
hollow, metal sphere. Owing to the In the OSTWALD COLOR SYSTEM, B is
shape of the body, most of the light the BLACK CONTENT in the equation
entering the opening is absorbed
inside the sphere and virtually
none emerges again. This aperture
is therefore black--i.e., the
"blackbody"--and, upon heating the
sphere, the light emerging is
W + B + C = 1, which OSTWALD
considered as describing the
appearance of all related colors.
solely composed of radiant power BLACK LIGHT [8]
due to the heating.
The spectral power distribution of
any incandescent light source can
be stated in terms of the absolute
temperature at which a blackbody
emits rays of the same WAVELENGTH
DISTRIBUTION. This temperature is
referred to as the COLOR TEM=PERATURE of the LIGHT.
Apart from the above mentioned
sphere, there is no such thing as
a perfect blackbody; all substances
Black light is the name for ultra-
violet illumination when it is used
to make objects visible in the dark.
The objects are treated with a dye
or pigment which fluoresces under
the ultraviolet radiation.
The source consists of a mercury
arc or other suitable light
screened by a filter (e.g., covered
with a lacquer) which cuts out all
the visible rays but the ultraviolet.
.reflect a certain amount of light BLEACH
which mixes with that emitted on
heating. So the spectral composi-
tion of the light they emit is not
absolutely proportional to their
temperature. In many cases,
however, the discrepancy is not
serious.
(1) To make whiter.
(2) A chemical used for bleaching.
(3) In color processing, a solu-
tion that changes all developed sil-
ver into soluble silver salts for
later removal.
(4) In black and white processing,
a solution to remove developed
silver. Part of the process of
changing from a negative to a
Radiant power emitted from a black- positive transparency.
body and having the SPECTRAL POWER
DISTRIBUTION given by PLANCK'S LAW,
i.e., a distribution determined
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BLEACHING [8] Note: See Figure 1 in the Appendix.
Converting a silver image BLISTERS [4]
(negative or positive) into a more
or less colorless silver compound, Small bubbles formed under the
such as silver chloride, bromide, emulsion due to the detachment
iodide, or complex salts containing of the emulsion from the paper or
chromates, ferrocyanides, etc., of film.
other metals as well. Bleaching
forms the initial stage of a large Bubbles, elliptical in shape and
number of toning processes for larger than one-quarter inch.
transparencies and prints (where
the additional metal compounds BLOCKED UP [4]
often produce the color of the
toned image), as well as many Applied to highlights in a photo-
intensification methods. graphic negative which are so
BLEACH-OUT PROCESS [5]
overexposed or overdeveloped that
no detail is visible.
A process for making color prints BLOOM 151
from a color transparency, by
using a support coated with a
mixture of dyes, each of which is
capable of being decolorized by
exposure to light in a different
An appearance characteristic of
high-gloss surfaces where the
highlights have a hazy border.
portion of the spectrum or by BLUE [5]
subsequent chemical action
controlled by a photographic image. (1) The hue visual sensation
BLIND SPOT (OPTIC DISC) [5]
An irregular area in the retina
which is not sensitive to light-
stimulation because it lacks rods
and cones. The exit point of the
OPTIC NERVE.
Note: The blind spot is around
6.5? of visual angle in diameter
and is situated about 15? to the
nasal side of the center of the
retina, corresponding to the
place of exit of the optic nerve.
The blind spot explains the
substantial gap in the temporal
typically evoked by stimulation
of the normal human eye with
radiation of wavelength approx-
imately 476 nanometers.
(2) Any hue predominantly
similar to that of the typical
blue.
(3) The COMPLEMENT of YELLOW.
A rare type of partial color-
blindness, in which blue and
yellow stimuli are confused
because the color gamut is
side of the monocular visual space. reduced to reds, greens, and grays.
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BLUE-YELLOW BLINDNESS (Continued)
See Also: TETARTANOPIA
BLURRY [5]
Having uncertain outlines.
BLURRED NEGATIVES [4]
Any negative showing indistinct
outlines of the image or double
outlines is "blurred". This may
be due to: (1) A poor lens,
(2) Camera out of focus,
(3) Camera motion, (4) Image
motion, (5) Platen vacuum failure.
BOSTROM TEST
A defective color-vision test
based on colored figures being
perceived on a differently colored
background. Not extensively used
or known.
BOUGER'S LAW [6]
(1) Stated formally: for a
molecularly dispersed colorant
of a given concentration, the
transmitted flux (It) of single-
frequency light of wavelength A
is a function of the incident
flux (Io), the EXTINCTION COEFFI-
CIENT (aA) and the thickness
(1) of the medium:
I = I e.a X1
t 0
(2) A mathematical expression
relating transmittance of a single
wavelength through a colored
medium to the INCIDENT FLUX,
EXTINCTION COEFFICIENT, and thick-
ness of the medium. More simply,
equal layers of a transparent
material absorb equal fractions
of each kind of energy entering
them.
(3) Also known as LAMBERT'S LAW,
but not the same as LAMBERT'S
COSINE LAW.
BRIGHT [5]
BRILLIANT, lively in appearance,
opposite of dull. Characterized
by a relatively high degree of
BRIGHTNESS.
BRIGHTNESS [5]
(1) Brightness is the LUMINOUS
INTENSITY of any surface in a
given direction per unit of
projected area of the surface
as viewed from that direction.
B = dI6/dA cos 6
where I = Intensity, A - Area,
and 6 is the angle between the
direction of observation and the
normal to the surface.
(2) In common usage, the term
brightness usually refers to
the INTENSITY of sensation which
results from viewing surfaces
or space from which light comes
to the eye. This sensation is
determined in part by the
definitely measurable "bright-
ness" defined above and in part
by conditions of observation,
such as the state of adaptation
of the eye.
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BRIGHTNESS (Continued) BRIGHTNESS RANGE [8]
Term indicating the ratio of the
BRILLIANCE of the extreme high-
lights to the darkest shadows of
a scene or image.
brightness of a surface generally BRIGHTNESS RATIO [5]
Note: In the defining equation
above, A is the angle between the
direction of observation and the
normal to the surface. In prac-
tice, few surfaces follow exactly
the Lambert's Cosine Law of
emission or reflection; hence, the
is not uniform but varies with the
angle at which it is viewed.
Brightness can be measured not
only for sources and illuminated
surfaces, but also for virtual
surfaces such as the sky.
The ratio of the brightnesses of
any two surfaces. When the two
surfaces are adjacent, the
brightness ratio is commonly
called the BRIGHTNESS CONTRAST.
The perceptual phenomenon in which BRIGHTNESS THRESHOLD, ABSOLUTE
an object appears to have the same
brightness under various levels The minimum LUMINANCE level of
of illumination. , a stimulus (with a particular
A BRIGHTNESS difference between
a visual area and its surrounding.
The greater the difference, the
higher the contrast.
Note: The equation is
LIo-LIb
LIb
where LI = Luminous Intensity,
o = object, and b = Background.
See Also: BRIGHTNESS RATIO
BRIGHTNESS PURITY
See LUMINANCE PURITY
SPECTRAL DISTRIBUTION) required
for the stimulus to be seen.
The value is determined after
complete DARK ADAPTATION but
does not exclude the effect of
processes normally active in the
sense organ.
Note: The absolute Brightness
Threshold under optimal condi-
tions is about .001 to .005 foot-
lambert for FOVEAL CONES and
.000001 foot-lambert for RODS 161.
BRIGHTNESS THRESHOLD, DIFFERENTIAL
The JUST-NOTICEABLE DIFFERENCE
between two brightness levels,
or Bob where B = Brightness,
o+Bb
o = object and b = background.
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BRIGHTNESS THRESHOLD, DIFFERENTIAL BULK COLOR
(Continued)
Note: The Differential Brightness
Threshold under optimal conditions BURNHAM-CLARK-MUNSELL COLOR MEMORY
is about .02 to .05 over an TEST [6]
extended range of luminance
(about 1 to 1,000 foot-lamberts).
Another name for LUMINOSITY, i.e.,
the intensity of light reflected
from a surface (incident light
intensity X reflectivity of
surface)'.
A short-term color memory test
in which the subject looks at
a color chip for 5 seconds, and
then it is covered. Five seconds
later the subject chooses from
a group of 43 differently colored
chips the one which matches the
covered chip. 20 colors are tested.
People are scored "Superior",
"Normal", or "Low".
The maximum brightness sensation
occurring .05 to .2 seconds after
the onset of a steady (state) light.
BROWN
A dark orange
BRUNSWIK RATIO [11]
A measure of COLOR CONSTANCY. A
ratio which indicates the degree
an object retains its color when
viewing conditions are changed.
Note: The ratio is expressed as
S-S' where L = luminance of
L-S'
unshadowed area,
S' = luminance of shadowed area,
and S = luminance of the exper-
imental match to the shadowed
area.
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CALLIER QUOTIENT [4]
The ratio between DIFFUSE and
SPECULAR DENSITY as measured on
a given photographic emulsion
(also called "Q-Factor").
Note: A low Q-factor means that
light is being absorbed rather
than being scattered by the
emulsion. A high Q-factor means
the opposite is occurring.
CAMOUFLAGE'DETECTION FILM
See COLOR INFRARED FILM
CAMPIMETRY
The measurement of the extent
colors are perceived from the
FOVEA. The test uses a Campimeter
which is a flat chart for mapping
the color sensitivity of the
entire RETINA.
CANDELA (Formerly CANDLE) [4]
The international unit of
LUMINOUS INTENSITY of a source
of light; the luminous intensity,
in the direction normal to a
BLACKBODY surface of 1/600,000
sq. meter in area at the tem-
perature of solidification of
platinum under a pressure of
101,325 newton/meter2.
Note: See Figure 4 in the
Appendix.
CANDLE [4]
See CANDELA
CANDLEPOWER [4]
LUMINOUS INTENSITY expressed in
terms of the CANDELA.
Note: Use as "The Candlepower
of the light source is 60
candelas".
CARDINAL POINTS [4]
In a thick lens system, the two
PRINCIPAL POINTS, the two NODAL
POINTS, and the two FOCAL POINTS.
CARDINAL STIMULI [5]
Four standard visual stimuli by
means of which the three reference
stimuli and the basic stimulus
of any TRICHROMATIC system may
be defined. For example, light
of wavelengths 700, 546.1 and
435.8 nm and Illuminant B have
been used by the CIE.
Note: Any three-color system
should have red, blue, and
green stimuli plus an illuminant.
Cardinal stimuli are simply those
colors and the illuminant chosen.
See Also: CIE COLOR SYSTEM; CIE
SOURCES; TRICHROMATIC COLOR
SYSTEMS.
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CEILING
The height above the earth's
surface of the lowest layer of
clouds or obstruction phenomena
that is reported as "broken", "over-
cast", or "obscuration" and not
classified as "thin" or "partial".
Note: Preferably, color should be
acquired when there is no ceiling
(full sun) and must be acquired
below ceiling.
CELSIUS (?C)
Formerly known as Centigrade. A
temperature scale in which the
freezing point of water is
labelled 0? and the boiling point
1000.
A measure of length; 1/100 of a
meter; abb.: cm
CENTIGRADE (?C.)
Now known as CELSIUS.
CHARACTERISTIC CURVE (H AND D CURVE;
SENSITOMETRIC CURVE; D LOG E CURVE)
A curve showing the relationship
between exposure and resulting
density in a photographic image,
usually plotted as the optical
density D [D = log (1/T)
(T-Transmittance or amount of
light passing through an area
divided by the total amount of
light striking the area) or degree
of blackening of an exposed film]
against the logarithm of the
exposure (log E) in candela-meter-
seconds.
Note: In the Figure below is a
set of Characteristic Curves
for the three dye. layers of a
color film where'A is the TOE; B
is a STRAIGHT LINE portion, and C
is called the SHOULDER. The
Characteristic Curve is extremely
important and from it can be
obtained (in part) the ASA SPEED
of the film, CONTRAST, EXPOSURE
LATITUDE, D-MAX, D-MIN, and GAMMA.
Log E
CHEMICAL FOG [4]
DENSITY produced on photographic
paper or films by chemical means
such as too energetic or
contaminated DEVELOPER.
The tissue layer, which contains
many blood vessels to nourish the
eye, that lies between the SCLERA
(outer tissue of the eye) and the
RETINA.
Note: See Figure 1 in the APPENDIX.
CHROMA
(1) Synonomous with SATURATION
(but also with COLOR).
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Note: In the Figure below, blue,
green, and red wavelengths are
(2) The dimension of the MUNSELL focused on different planes
COLOR SYSTEM which corresponds most because of longitudinal chromatic
closely to saturation. aberration.
Note: The word CHROMA has been
used in many ways. To avoid
confusion it should only be used
with reference to the Munsell
Color System. Otherwise use the
term "saturation".
See Also: MUNSELL COLOR SYSTEM;
SATURATION; VIVID.
A binocular illusion of depth CHROMATIC COLOR [5]
which occurs when viewing small,
highly saturated targets or areas A color which has HUE and
against homogeneous backgrounds of SATURATION.
a widely separated wavelength,
e.g., a red body against dark blue See Also:. ACHROMATIC COLOR (for
water. The target will appear to comparison)
stand out from the background even
though it may have no height; if CHROMATIC CONTRAST
it does have height, it will be
exaggerated.
Chromatic means having some
perceptible degree of SATURATION
and HUE.
CHROMATIC ABERRATION [4]
CHROMATIC DISCRIMINATION [18]
Ability to distinguish
CHROMATICITY differences.
CHROMATIC FLICKER [5]
A defect (unequal REFRACTION) in
a lens which causes rays of light
of different wavelengths to be
brought to a focus at different
points in the space. There are
two types: LONGITUDINAL CHROMATIC
ABERRATION and LATERAL CHROMATIC
ABERRATION.
A pulsating or flicker phenomenon
caused by differences in HUE and
SATURATION, either singularly
or combined, that occurs between
stimuli of equal LUMINANCE which
are alternately applied to the
same retinal area.
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CHROMATIC FLICKER [5]
(.Continued)
White Fluore-
Note: Distinguished from flicker
scent Lamp
(4500 K)
0.359
0.363
in general which may involve
pulsations in brightness.
White Fluore-
scent Lamp
(3500 K)
0.404
0.396
CHROMATIC RESOLVING POWER
See RESOLVING POWER, CHROMATIC
CHROMATICITIES OF CIE STANDARD
SOURCES [5]
The chromaticities of the CIE
standard for COLORIMETRY are:
Source A x = 0.4476 y = 0.4075
Source B = 0.3485 0.3518
Source C = 0.3101 = 0.3163
Source D65 = 0.3127 = 0.3291
See Also: CIE SOURCES; DAYLIGHT
D ILLUMINANTS
(1) The quality of a color
specified by DOMINANT WAVELENGTH
(alternatively, COMPLEMENTARY
WAVELENGTH for purples) and PURITY,
taken together.
(2) In the CIE system of color
measurement, Chromaticity is
expressed mathematically by two
numbers, x and y, termed
CHROMATICITY COORDINATES; a
diagram showing the ranges of
these coordinates for all colors
is termed a CHROMATICITY DIAGRAM.
CHROMATICITIES OF OTHER IMPORTANT
SOURCES AND ILLUMINANTS [5]
The approximate chromaticities of
various sources and illuminants
are indicated by the following
CHROMATICITY COORDINATES:
Sunlight x = 0.336 y = 0.350
Average
Daylight 0.313 0.328
North Sky
Light 0.277 0.293
Zenith Sky 0.263 0.278
White Flame
Carbon
Arc 0.315 0.332
Daylight
Fluore-
scent
Lamp
(6500 K) 0.313 0.329
Note: CHROMATICITY is equivalent
to the common concept of quality
as distinguished from quantity of
light.
In the CIE system, they are the
ratios of each of the three
TRISTIMULUS VALUES (X, Y, and Z)
of a sample color to the sum of
the tristimulus values:
X ,
X + Y + Z
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CHROMATICITY COORDINATES (Continued)
They are the coordinates for the CIE COLOR DIFFERENCE FORMULAS AND
CHROMATICITY DIAGRAM; See Figure 2 UNITS
in the Appendix.
See COLOR DIFFERENCE FORMULAS AND
CHROMATICITY DIAGRAM UNITS
A plane diagram formed by plotting CIE COLOR MATCHING FUNCTIONS
one of any set of three
chromaticity coordinates against See COLOR MATCHING FUNCTIONS
another.
CIE COLOR SYSTEM
Note: See Figure 2 in the Appendix
for an example of the Diagram.
CHROMATOPSIA [5]
An abnormal state of vision in
which colorless objects appear
colored. For example, yellow after
santonin, red after snow-
blindness.
Dye formed as a result of the
chemical reaction between the
oxidized COLOR DEVELOPER (the
exhausted form remaining after the
DEVELOPMENT of image silver) and
the DYE COUPLER.
CHROMOSCOPE [5]
A type of colorimeter using color
produced by the rotary dispersion
of quartz as standards. Somewhat
out-of-date.
Abbreviation for Commission
Internationale de 1'Eclairage, the
French title of the International
Commission on Illumination.
The CIE Color System is a color
designating system based on the
physical aspects of light and
color perception.
Note: This system is too complex
to fully describe here. The
reader is referred to references
[1], [6], and [17].
CIE DISTRIBUTION COEFFICIENTS
See DISTRIBUTION COEFFICIENTS
CIE ILLUMINANTS (CIE STANDARD
ILLUMINANTS)
Spectral power distributions
defining standard illuminants for
colorimetric calculations.
Included are the spectral power
distributions of CIE SOURCES A, B,
C and the spectral power
distributions defining the CIE
Daylight D illuminants.
See Also: DAYLIGHT D ILLUMINANTS
CIE PURITY
See PURITY
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CIE SOURCES (CIE STANDARD SOURCES) ICI standards or (in Germany) IBK
standards.
Source A: A gas-filled
incandescent lamp operating at CIE TRISTIMULUS VALUES
2854 K.
Source B: Same as above, but with
a filter to produce an CILIARY BODY
approximation to noon sunlight.
(COLOR TEMPERATURE of 4870 K).
Source C: Same as A, but with a
filter to produce an approximation
to overcast skylight. (Color
temperature of 6740 K).
Note: See Figure below:
p. 1
Wavelength, nm
A body of tissue which contains
three groups of muscle fibers to
change the shape of the LENS of
the eye during focusing.
Note: See Figure 1 in the
Appendix.
CINCHING [4]
Tightening a roll of film by
holding the spool and pulling the
free end; frequently results in
parallel scratches or abrasion
marks.
CIRCLE OF CONFUSION (CIRCLE OF LEAST
CONFUSION) 14]
The circular image of a distant
point object as formed in a focal
plane by a lens. A distant point
object (e.g., a star) is imaged in
a focal plane of a lens as a circle
of finite size because of lens
aberrations. .
See Also: CHROMATICITIES OF CIE
STANDARD SOURCES; DAYLIGHT D
ILLUMINANTS
Standards of illuminants and of
color perception set up by the
Commission Internationale
de l'Eclairage (International
Commission of Illumination) to
provide a means of accurately
describing colors. Also known as
CLARITY OF COLOR 15]
Clarity of color means clearness of
color in contrast to muddiness.
CLEAN (CLEAR) [5]
Free from a tendency to be dull,
dingy, gray, dusty, or CLOUDY in
appearance.
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CLOUDY [5]
Blotchy, uneven color of "milky"
appearance.
COATED LENS [4]
A lens whose surfaces have been
coated with a transparent film of
such thickness and index of
refraction as to minimize the
light loss due to reflection.
See Also: ANTI-REFLECTION
COATINGS
COLLIMATING LENS (COLLIMATION
OPTICS) [4]
A lens or optics which makes
convergent or divergent rays
parallel.
(1) The process of making light
rays parallel.
(2) The process of aligning the
OPTICAL AXES of optical systems.
COLOR [4]
(1) A general term for the
quality of light distinguishable
by the visual sense, e.g., black,
white, gray, light blue, red, dark
yellow, etc.
(2) That property of an object
which is dependent on the
wavelength composition of the
light it reflects, emits, and
transmits.
See Also: CHROMATIC COLOR; ACHRO-
MATIC COLOR; METALLIC COLOR
The ability to work with colors,
e.g., color naming, color matching,
color discrimination, and a good
color memory. This aptitude can
be improved with practice and
experience with colors.
A collection of color samples
usually used for visual matching.
COLOR BALANCE [4]
(1) The relative adjustment of
the overall intensities of the
ADDITIVE or SUBTRACTIVE PRIMARIES
in a color reproduction in order
to give the best reproduction.
(2) The proper intensities of
colors in a color reproduction
which, when balanced, give a
correct reproduction of the gray
scale.
Note: Color balancing is a complex
processing problem. Lack of proper
balancing may result in imagery
having a bluish, reddish,
yellowish, etc., appearance.
However, it should be noted that
the reverse is not always true,
i.e., yellowish imagery is not
necessarily due to improper color
balancing.
Color vision defect marked by a
partial (DICHROMATIC VISION;
ANOMALOUS TRICHROMATIC VISION) or
a total loss of color vision
(MONOCHROMATIC VISION).
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The photographic image on a
negative may be pure black or it
may be colored. If the color is
non-actinic with respect to the
printing paper used, the print
obtained will have more contrast
than one from an untinted, but
otherwise identical, negative.
The ratio of the GAMMA of the
colored negative, as determined
from the print made from it, to
the gamma of an otherwise
identical negative is termed the
Color-Coefficient, or the Color-
Coefficient of contrast.
COLOR, CLASSES OF [5]
Colors may be divided generally
into two distinct classes,
CHROMATIC and ACHROMATIC.
Colors generally do not appear to
change with varying illumination
levels or types even though the
wavelength composition may have
changed.
Note: A U. S. Army vehicle that is
partially shaded may appear to
have the same continuous olive-
drab color when, in fact, the
shaded portion is a darker color.
See Also: BRUNSWIK RATIO;
THOULESS RATIO
COLOR CONTRAST
See CONTRAST, COLOR
COLOR CONVERSION [18]
Change in any dimension of
ACHROMATIC COLORS vary only in perceived color due to change in
BRIGHTNESS. CHROMATIC COLORS vary any conditions of viewing.
in BRIGHTNESS, HUE, and SATURATION.
COLOR CO-ORDINATE TRANSFORMATION [7]
See Also: METALLIC COLORS
COLOR COMPARATOR
An instrument designed for the
comparison of colors.
Computation of TRISTIMULUS VALUES
of colors in terms of one set of
PRIMARIES from the tristimulus
values of the same colors in terms
of a different set of primaries.
Note: The widest use of color
comparators is the determination
of the concentration of a known
constituent in a solution; such
instruments are sometimes called
Chemical Colorimeters.
COLOR COUPLERS (DYE COUPLERS)
Chemicals that form dyes in the
emulsion by reacting with the
oxidized products formed during
DEVELOPMENT. The amount of dye in
any one place is proportional to
the exposure in that layer of the
color film.
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VISION, DICHROMATIC VISION, and
ANOMALOUS TRICHROMATIC VISION.
A term usually applied to lenses or
optical systems to refer to their COLOR DENSITOMETER
designs which insure that they
minimally alter or imbalance the
wavelengths of light passing
through.
Note: For example, lenses which
focus red at a different plane than
blue are not Color Corrected.
Color imagery and panchromatic
films (sensitive to a wide range
of wavelengths) must be acquired
with Color Corrected optical
systems.
COLOR CORRECTION FACTOR (to a
photometer)
The factor by which the readings
of a PHOTOMETER must be multiplied
in order to obtain values in
conformity with the VX function
for light of a spectral
composition different from that by
which the photometer was
calibrated.
A device which measures the
RADIANT FLUX for three bands of
wavelengths (red, blue, green) by
using three filters whose peak
absorption wavelengths are at or
near the absorption peaks of the
three colorants used in the color
reproduction being measured.
The measurement of dye densities
in color reproductions. There are
two major types of measurements:
ANALYTICAL DENSITOMETRY and
INTEGRAL DENSITOMETRY.
COLOR DEVELOPER [5]
A chemical substance or mixture of
substances capable of reducing
silver halides with the
simultaneous production of an
insoluble colored product (a DYE)
in regions of the silver deposit.
Mathematical formulas used to
express numerically the perceptual COLOR FIDELITY
difference between two colors.
Note: There are many different
formulas, all which disagree with
one another and none of which
agree perfectly with visual
perception.
A general term for all forms of
color vision different from
normal. Includes MONOCHROMATIC
A term generally applied to the
degree that colors on an image
match those of the original scene.
Note: No known color film has
perfect color fidelity although
fidelity is quite good when
acquired properly. Color Fidelity
is severely affected by
atmospheric attenuation and
improper exposure settings.
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A compound added to the emulsion
layer which reacts with the
oxidized COLOR DEVELOPER to form
specifically colored dyes, e.g.,
YELLOW DYE, MAGENTA DYE, and
CYAN DYE.
The range of colors produced by a
given method.
COLOR INFRARED (IR) FILM
A Kodak false-color film
(Ektachrome Infrared 8443) which
is also known as Camouflage
Detection film. The emulsion
layers are sensitive to green,
red, and infrared wavelengths.
Living vegetation emits
infrared wavelengths and appears
red on the film and dead
vegetation appears yellowish/
brownish on the film. Thus,
dead vegetation used as
camouflaging materials can be
distinguished from living
vegetation.
COLOR INTERVAL [5]
The degree of visual difference
between two colors measured in
steps of HUE, VALUE, and CHROMA.
Any two visual sensations which
appear to be the same in terms of
color.
The procedure of determining
whether two visual sensations are
the same in terms of color.
Color matching is usually done
with a sample color and a set of
reference colors. One attempts to
select one of the reference colors
which has the same (or nearly the
same) color as the sample color.
Note: Color matching should be
done with the same type and
intensity of illuminant and the
eyes must be LIGHT-ADAPTED.
See Also: VISUAL COLORIMETRY,
INSTRUMENTAL COLORIMETRY
In the CIE color system they are
designated as x, y, and z and
represent the color matching pro-
perties of a standard observer.
Note: See Figure below for the
distributions.
500 600
Wavelength, nm
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11
COLOR MATCHING FUNCTIONS (Continued) COLOR PHOTOGRAPHY [4]
See Also: STANDARD OBSERVER The reproduction of subject or
scenic matter in natural colors by
COLOR MIXTURE photography.
The combination of two or more COLOR POSITIVE FILM
colors.
A photographic film whose colors
COLOR-MIXTURE DATA after DEVELOPMENT are nearly the
same as the original
(1) The amounts of red, blue, and scene.
green light needed to be combined
to perceive a particular color. COLOR PYRAMID
and green) to establish a color COLOR RENDERING
match with a sample color.
(2) The'amounts of the
colorimetric primaries (red, blue,
A photographic film whose colors
after DEVELOPMENT are COMPLEMENTS
of the original scene.
COLOR NORMAL
A person with normal color vision.
See NORMAL TRICHROMATIC VISION
COLOR NOTATION
Symbols arranged in some orderly
fashion by which the attributes
of color may be communicated
either verbally or written. For
example, in the MUNSELL COLOR
SYSTEM the Color Notation 5Y 4/10
is used to communicate a
particular yellow color.
The visual experience of color.
The effect a light source has on
the appearance of colors compared
to the effect produced with a
standard or reference light source.
A measure of the degree to which
the perceived colors of a set of
test objects illuminated by a
source as compared to their per-
ceived colors when illuminated by a
standard source under specified
conditions. The index ranges from
0 to 100. An index of 100 means
that the source affects the
appearance of color the same as
the standard. An index of 50 is
an example of the shift from
fluorescent light to incandescent
light.
Note: The basic problem with this
index is understanding what the
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COLOR RENDERING INDEX (Continued)
numbers mean in terms of perceived
colors. For example, how the
colors are perceived when illu-
minated by a source with an index
of 83 is difficult to determine.
COLOR REVERSAL FILM
See REVERSAL FILMS, COLOR
COLOR SCALE [5]
An orderly arrangement of colors
showing graduated change in HUE,
SATURATION, or BRIGHTNESS.
COLOR SENSATION [5]
Any visual experience of a
CHROMATIC nature which results
from stimulation of the retina,
as distinguished from the physical
considerations descriptive of the
stimulus.
The variations in brightness or
lightness of a color, e.g., light
red, dark red.
COLOR SOLID [5]
A symbolic figure in three dimensions
which represents the relations of all
possible colors with respect to their
primary attributes of hue, brightness
or lightness, and saturation.
Usually brightness (lightness)
appears as the vertical axis of the
figure, with hue and saturation
represented in polar coordinates
about the brightness axis, and
saturation being radial. The
boundaries of the solid are actually
irregular, but it is sometimes
represented as a cylinder, a sphere,
a spindle, a double cone or a double
pyramid with a common (square or
triangular) base.
COLOR SPECIFICATION [5]
A description of a color made in
The sensitivity of a photographic such a way that the color
emulsion or the retina of the eye sensation may be duplicated. This
to light of various wavelengths. may be done with the aid of
certain visual color matching
devices, such as COLORIMETERS or
COLOR COMPARATORS.
The separate photographic records
(usually 3 panchromatic negatives) See Also: COLOR NOTATION
of the relative intensities of the
primary colors (reds, greens, or COLOR STANDARD
blues) in a scene or color image
(transparency or print).
See Also: ADDITIVE COLOR
SEPARATIONS
A color whose dimensions of HUE,
SATURATION, and BRIGHTNESS have
been accurately measured and
specified and then used for
comparison purposes.
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COLOR STANDARD (Continued)
Note: Munsell chips are in a
sense Color Standards when they
are used to determine the name or
designation of other colors.
COLOR STIMULUS [5]
(1) RADIANT ENERGY of any
luminance and wavelength
composition within the ranges
which are capable of adequate
stimulation of retinal receptors.
(2) The term is sometimes limited
to adequate stimuli for evoking
the sensation of HUE.
COLOR SURFACE [5]
A plane section of a COLOR SOLID
(usually taken perpendicular to
the axis of brightness variation)
that represents all possible hues
and saturations at a single
brightness level.
The temperature (in Kelvin)
of a ]3LACKBODY radiator whose
SPECTRAL DISTRIBUTION matches that
of the color being designated.
Note: The blackbody colors form
a single series of relatively
unsaturated visual qualities,
ranging from red, through orange,
white, pale blues, and violets
as the temperature is increased.
For example, if a light source has
a SPECTRAL DISTRIBUTION which
matches that of a blackbody at
3,000 Kelvin, then the light
source is said to have a Color
Temperature of 3,000 Kelvin.
See Also: CORRELATED COLOR
TEMPERATURE; RECIPROCAL COLOR
TEMPERATURE; BLACKBODY; MIREDS
The luminance below which color
becomes no longer discernible.
The level varies for different
colors, but minimum is about 103
candelas/square meter at which
red is first perceived.
COLOR TRANSPARENCY [5]
A color photograph upon a glass
or film support to be viewed or
projected by transmitted light, as
distinguished from a color
photograph on paper or other
opaque white support to be viewed
by reflected light.
COLOR TRIANGLE [5]
A diagram (typically) in the form
of an equilateral triangle with
apices representing red, green,
and blue primaries and the
enclosed area representing all the
CHROMATICITIES possible by
additive mixture of these three
primaries.
Note: Characteristic of the color
triangle is the adjustment of the
primary scales so unit amounts
will yield an achromatic mixture
which is represented by the
centroid of the triangle; and the
relative amounts of the primaries
necessary to yield each
chromaticity are then indicated by
corresponding distances on the
triangle.
See Also: COLOR SOLID;
CHROMATICITY DIAGRAM; MAXWELL TRIANGLE
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COLOR VISION [5]
Vision with the response of
CHROMATIC COLORS.
See Table 2 in the Appendix for
brief descriptions. Individual
theories listed in Table 2 may
also be found in the Glossary.
COLOR WEAKNESS [5]
A defect in color vision marked by
diminished color sensitivity
rather than actual loss of
sensitivity to any HUE.
See Also: ANOMALOUS TRICHROMATIC
VISION
COLOR ZONES (COLOR FIELDS) [5]
Regions of the retina which have
different characteristics as to
chromatic color response.
Note: For most individuals and
usual conditions, the central
region shows full chromatic color
response, while red and green
responses disappear at a
moderately peripheral position
and blue and yellow fail toward
the extreme periphery. The exact
size boundaries of any zone depend
upon the size, intensity, and
saturation of the stimulus used;
they also vary with the
individual and with the
measurement technique employed.
See Also: CAMPIMETRY; PERIMETRY.
A DYE or PIGMENT which
selectively absorbs particular
wavelengths.
COLORED SHADOW PHENOMENON [5]
An accentuated type of
SIMULTANEOUS COLOR CONTRAST
observed when two shadows are cast
upon the same surface near each
other by two lights of different
color; when the shadows are made
about equal in brightness, each one
tends to appear of a color
COMPLEMENTARY to that of the light
which casts it.
COLORIMETER [5]
A color measuring instrument for
comparing a known color to an
unknown color so that the latter
is specified in terms of the
former. The colorimeter may be
calibrated or the specification
may be transformed to yield a
measurement in terms of some
standard system of colorimetry.
Note: Generally, the instrument
is used to determine approximate
CIE Tristimulus values X, Y, and Z
for a transparent or opaque sample.
See Also: SPECTROPHOTOMETER:
TRISTIMULUS COLORIMETER
The science of measuring color and
expressing colors numerically.
The measurements can be made
visually or with devices.
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COLORIMETRY (Continued)
See Also: VISUAL COLORIMETRY;
INSTRUMENTAL COLORIMETRY
Density measurements on color
films (using the STANDARD
OBSERVER) used to determine how
the colors will appear to the
standard observer.
A lens aberration affecting the
sharpness of images off the
OPTICAL AXIS which causes oblique
light rays from a point source to
be imaged as a comet-shaped blur.
Thus objects will appear out-of-
focus.
COMPARISON LAMP [5]
A Comparison Lamp is a lamp of
constant but not necessarily known
candlepower against which standard
A PHOTOMETER designed to measure and test lamps are successively
the intensity of light of different compared in a PHOTOMETER.
colors through the use of filters
COLORIMETRIC PHOTOMETER [4]
interposed in the path of the
light.
COLORIMETRIC PRIMARIES [5]
Any three colors which are
additively mixed to match an
unknown color when making a
colorimetric measurement.
Representative red, green, and
blue stimuli are most commonly
used as Colorimetric Primaries;
but theoretically any three colors
can be used if the color of any
one cannot be matched by mixing
the other two.
COLORIMETRIC PURITY [5]
EXCITATION PURITY multiplied by
the ratio of the luminances of the
spectrum color and the sample
color.
Note: In the case of purples, the
calculation is made using the
spectrum color corresponding to
the COMPLEMENTARY WAVELENGTH of
the sample color.
One of a pair of colors (from light
sources) which when mixed produces
a neutral gray, white, or black.
One of a pair of COMPLEMENTARY
COLORS.
Note: Red is the Complement of
Blue-Green; Green is the Complement
of Blue-Red; Blue is the Complement
of Yellow; and vice versa.
COMPLEMENTARY COLORS (COMPLEMENTS)
[7]
,Two colors (from light sources)
which when combined in the proper
amounts mix to produce an
ACHROMATIC COLOR.
Note: Complementary Colors are
red -- blue-green (CYAN), green --
red-blue (MAGENTA), blue--
(YELLOW).
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COMPLEMENTARY WAVELENGTH(S)
The wavelength(s) of light which
when combined in suitable propor-
tions with another color and
matches an adopted ACHROMATIC
COLOR is the Complementary
Wavelength of the other color.
the center of the retina (FOVEA)
the cones are long and slender and
closely packed to the exclusion
of rods and farther out they are
shorter and thicker and
interspersed among the more
numerous rods. It is estimated
that there are 7,000,000 Cones in
the human retina.
Note: The wide variety of purples
(including nonspectral violet, CONDITIONAL MATCH
purple, magenta, and nonspectral
red colors) which have no DOMINANT
WAVELENGTHS are specified by use
of their Complementary Wavelengths
in the CIE COLOR SYSTEM.
COMPLETE DIFFUSION [5]
A match between two colors which
is agreed upon by most observers
under most light sources.
The tendency of colors to attract
Complete diffusion results when a attention, particularly on color
diffusing medium scatters the transparencies.
light upon it so completely that
none is regularly reflected or Note: The term is derived from
transmitted, and objects from the word "conspicuous" which means
which the light originally came standing out from the background
cannot be distinguished. and immediately noticeable.
CONE, RETINAL [5] CONSTANCY
A type of minute structure found See COLOR CONSTANCY; BRIGHTNESS
in the retina of the eye which CONSTANCY
constitutes a specific receptor
for color vision. Distinguished CONTACT PRINT [4]
from retinal RODS, another visual
receptor; the cones are without A print made by placing a negative
visual purple (the chemical in contact with sensitive paper
Rhodopsia) and are believed to while exposure is being made.
operate for both CHROMATIC and
ACHROMATIC (gray) visual qualities CONTINUOUS SPECTRAL DISTRIBUTION
at higher levels of illuminations;
the rods for achromatic only at A SPECTRAL DISTRIBUTION that is
low (twilight) levels. Currently, never zero over a considerable
there are thought to be three types spectral range.
of cones sensitive to red, blue, or
green. The rods and cones form See Also: SPECTRAL DISTRIBUTION
the 2nd layer of the retina (from
the surface of the eyeball). At
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CONTINUOUS SPECTRUM [5]
A SPECTRUM or section of a
spectrum in which radiations of
all wavelengths are present.
CONTRAST [4]
In photography the difference
between highlights and shadows.
The ratio of reflecting power
between the highlights and shadows
of a print determines the contrast.
Contrast in a transparency is
determined by the ratio of the
DENSITIES of the parts compared.
CONTRAST, COLOR [5]
(1) The ratio of the intensities
of the sensations caused by two
colors. Sometimes the logarithm
of this ratio.
(2) Also used for SIMULTANEOUS
COLOR CONTRAST
Note: High color contrast means
that there is a large difference
between the two intensities of
two colors, e.g., yellow vs. black;
whereas low color contrast means a
small difference between the two
intensities, e.g., pink vs. red.
CONTRAST FACTORS [4]
The amount of contrast in a
finished photograph may be
attributed to several factors.
They include the exposure, the
filter used, the type of film, the
duration of negative development,
the duration of exposure and
development in printing, and the
paper used in printing.
CONTRAST FILTER [4]
A color filter chosen to make
a colored subject stand out very
sharply from surrounding
objects.
CONTRAST TRANSFER FUNCTION
See MODULATION TRANSFER FUNCTION
CONVERGENCE
The turning of the eyes inward as
objects are brought close.
COOL COLORS [5]
Colors of green or blue or colors
containing a marked predominance
of green or blue.
The transparent area at the front
of the eye and directly in front
of the pupil and lens.
Note: See Figure 1 in the
Appendix.
CORRECTION FILTER [8]
Term for any filter which alters
colors to suit the color response
of the film in use. Any color
filter can be regarded as a
correction filter.
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The color temperature of the
blackbody whose CHROMATICITY is
nearest that of the source
considered. Used when the spectral
power distribution of the source
does not match that of any
blackbody, even approximately.
For example, the chromaticity of
noon summer sunlight is closer to
that of the blackbody radiator
whose color temperature is 5740 K.
CRITICAL ANGLE [12]
The angle beyond which total
INTERNAL REFLECTION of a ray takes
place when passing from a medium of
higher index to a medium of lower
index. The angle is expressed by
the equation sine A = N'/N, in
which A is the critical angle, N'
is the lower index of refraction,
and N is the higher index of
refraction.
Thus the correlated color CRYSTALLINE LENS
temperature of noon summer sunlight
is 5740,x, but the spectral power
distributions of noon summer
sunlight and a 5740 K blackbody
are quite different.
Note: Fluorescent lights (as in
light tables) have spectral
distributions which do not match
those of BLACKBODY radiators and
thus have Correlated Color
Temperatures.
COUPLER
. See COLOR COUPLER
COVERAGE, ANGLE OF
See ANGLE OF COVERAGE
CRAB [4]
The condition caused by failure to
orient the OPTICAL AXIS with
respect to the track of the
platform. In vertical
photography, crab is indicated by
the edges of the photographs not
being parallel to the air-base
lines.
The LENS of the aye lying
directly behind the AQUEOUS HUMOR;
the shape of which is changed by
the CILIARY BODY in order to
focus the visual image onto the
retina.
Note: See Figure 1 in the Appendix.
Features of the terrain that have
been constructed by man. Included
are such items as roads, buildings,
and canals; boundary lines; and,
in a broad sense, all items desig-
nated by names and legends on a map.
A lens aberration which causes a
flat object surface to be focused
as a curved image surface. All
good optical systems are corrected
for this aberration.
Note: See Figure below. On
imagery this aberration results in
only the outer portions of the
scene being out-of-focus.
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CURVATURE OF FIELD (Continued)
A curve showing the variation of
LUMINOUS INTENSITY of a light
source with the angle of emission.
CUTOFF FILTERS
See FILTER
CYAN [5]
The name applied to the blue-
green colors or the wavelength
of approximately 494 nanometers.
Cyan is the hue COMPLEMENTARY to
red.
During the processing of color
film, it is the blue-green dye
formed in the red sensitive layer.
Note: In positive transparencies
it is formed where red wavelengths
were not imaged, thus stopping the
transmission of red except where
it was imaged. In negatives it is
formed where red wavelengths were
imaged, thus allowing its
complement (CYAN) to be
transmitted.
See Also: YELLOW DYE; MAGENTA DYE
CYANINE (CYANIN)
Earliest known member of the class
of cyanine dyes, a very large
number of which have now been
synthesized. The great majority
of dyes used for sensitizing
emulsions are of the cyanine
class.
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D-LOG E
See CHARACTERISTIC CURVE
D-MAX [4]
The highest density which can be
obtained using a particular photo-
graphic material. When referring
to a particular negative or
positive, the highest density
recorded.
Note: On the CHARACTERISTIC
CURVE it is the highest density.
D-MIN. [4]
The lowest density on a positive
or negative.
Note: On the CHARACTERISTIC CURVE
it is the minimum density.
DALTONISM [5]
Named for John Dalton, 1766-
1844, who was himself color-blind
for red and green and published a
description of his case.
(1) Having the appearance of
reflecting only a limited amount
of light (tending toward BLACK).
(2) Dark colors are those of
relatively low BRIGHTNESS or
LIGHTNESS.
DARK ADAPTATION (DARKNESS
ADAPTATION)
An eye whose condition has been so
modified by the withdrawal of
general light that its sensitivity
to light has increased.
See Also: ADAPTATION, DARK
DARKROOM [4]
A room made free from light in
which photographic operations are
conducted. It is sometimes
illuminated with a SAFELIGHT the
rays of which are non-ACTINIC to
the film or paper.
DATUM [4]
Refers to a direction, level, or
position from which angles,
heights, depths, speeds, or
distances are conventionally
measured.
A special condition, usually due
to impairment of the central area
of the RETINA, in which the
individual sees better in dim
light.
The total visible RADIATION from
the sky and sun.
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DAYLIGHT (Continued) D
normal trichromatism and complete
dichromatism), and MONOCHROMATIC
Note: Its SPECTRAL POWER VISION.
DISTRIBUTION is shown in Figure 3
of the Appendix. DEFINITION [2]
See Also: SKYLIGHT; SUNLIGHT. Degree of clarity and sharpness of
an image.
DAYLIGHT D ILLUMINANTS
A series of CIE standard
illuminants whose spectral power
distributions are those of average
daylight. CORRELATED COLOR
TEMPERATURE is the variable within
the series. The most important
Note: A high degree of definition
means that edges and details are
sharp and colors are clear;
implying high resolution, focus
and good color fidelity, and
balance.
daylight D illuminant is D65, with DEGRADED COLOR
a correlated color temperature of
6500 K. Next in importance are
D55 and D75, with correlated color
temperatures of 5500 and 7500 K,
respectively. Formulas are
available for calculating the
spectral power distribution of any
D illuminant with correlated color
temperature between 4000 and
20,000 K. It is anticipated that
ultimately D65 will replace CIE
standard illuminants B and C for
colorimetric calculations.
DEEP COLOR
Colors which are highly saturated.
DEFECTIVE COLOR VISION [5]
The condition in which color
discrimination is significantly
reduced in comparison with that
of the NORMAL TRICHROMAT.
Note: The forms of defective
color vision can be divided into
three main groups - DICHROMATIC
VISION, ANOMALOUS TRICHROMATIC
VISION (all cases lying between
Colors which do not appear true or
correctly balanced.
DENSE [4]
A term applied to negatives or
positives in which the silver
deposit is heavier than normal
due to overexposure or over-
development.
DENSITOMETER [4]
A device used to measure the
OPTICAL DENSITY of deposits in a
photographic image. There are
many varieties, but all are alike
in providing a means for comparing
the intensity of a standard light
to that of an identical beam of
light which has passed through the
area to be measured. Comparison
between the two may be visual or
by photoelectric cells. For
determining the density of an
image on paper, a Reflection
Densitometer is used.
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A color measurement system based
on the Munsell Color System where
instead of determining a color by
matching with Munsell Chips, the
HUE, VALUE, and CHROMA are
determined with a DENSITOMETER and
a set of nomographs.
Note: Since a densitometer is
used, colors on transparencies can
be determined and referred to the
MUNSELL COLOR SYSTEM.
The technique of measuring
densities on photographic images.
Can be carried out by transmitted
light (e.g., on a transparency) or
by reflected light (e.g., on a
paper print). The instrument used
f h
Note: There are many different
ways of measuring densities on
color emulsions. See ANALYTICAL,
SPECULAR, DIFFUSE, INTEGRAL
DENSITIES.
See Also: ABSORBANCE; OPTICAL
DENSITY
The term usually refers to the
"rich" quality of highly saturated
colors.
DESATURATED COLORS (PALE COLORS)
Colors in which the SATURATION is
noticeably decreased as compared
with a standard.
or suc measurement is a DESATURATION (DESATURATE) [18]
DENSITOMETER; the results may be
used for plotting the Reduction in SATURATION.
CHARACTERISTIC CURVE of the
material concerned or for EXPOSURE DESENSITISERS (DESENSITISING) [11]
determination.
See Also: DENSITY; SENSITOMETRY;
COLOR DENSITOMETRY
(1) The quantity per unit volume,
area, or length.
(2) The degree of OPACITY as
defined as log10 1
Transmittance
or log10 I 1
Reflectance
A desensitiser is a substance
which when applied to a sensitive
emulsion reduces its sensitivity
to light. Most desensitisers
destroy, or partially destroy, the
LATENT IMAGE on an exposed film;
those that do not are mostly
dyes. These are of great value in
permitting even the fastest and
most color-sensitive films, after
a short treatment in total
darkness, to be developed in a
comparatively bright yellow
light.
(3) In EMULSION, it is the amount
of silver grains or color dye
globules in a given area.
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DETAIL [4]
The smallest discernible
differences (e.g., object edges
or colors) which are clearly
defined; good detail implies high
resolution and good focus.
DEUTERANOMALOUS VISION
(DEUTERANOMALY; a DEUTAN) [5]
DEVELOPER (Continued)
See Also: COLOR DEVELOPER
DEVELOPMENT [11]
Development is the production of
a visible image from the
invisible or LATENT IMAGE formed
on sensitive material by exposure
to light.
A form of ANOMALOUS TRICHROMATISM
in which more green is required in DEVELOPMENT BY INSPECTION [4]
a mixture of red and green to
match a spectral yellow than in Development of negatives or
the case of the NORMAL TRICHROMAT. prints using direct observation
The relative spectral visual and depending on the operator's
sensitivity does not differ judgment as to when development
noticeably from the normal but it is complete.
is less in the red to green region.
Hue discrimination is poor in the DIAPOSITIVE [8]
red to green region of the
spectrum. Positive image on a transparent
support intended for viewing by
Note: In the population, it transmitted light, e.g., a
affects about 4.8% of males and transparency.
.39% of females [6].
DEUTERANOPIA (a DEUTERANOPE)
Light entering the eyeball through
Form of DICHROMATIC VISION in the SCLERA layer (outer coating).
which green and purplish red
stimuli are seen as grays. The DICHROIC [5]
deuteranope sees only spectral
hues of blue and yellow and colors Pertaining to the ability of
mixed therefrom. some selectively absorbing
substances to vary in color with
Note: In the population it layer thickness or concentration.
affects about 1.1% of males and
.01% of the females [6].
DICHROIC FILTER [5]
A solution which converts the
exposed grains of silver halide to
metallic silver, forming the
negative image.
(1) A semitransparent mirror
which selectively reflects some
wavelengths more than others and
so transmits selectively.
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DICHROIC FILTER [5] (Continued)
(2) A filter transmitting two
narrow regions of the spectrum.
A term applied to a material which
selectively transmits and reflects
light depending upon its
wavelength.
DICHROMATIC VISION (a DICHROMAT)
A form of defective color vision
in which only two regions of the
visual spectrum can adequately be
perceived.
Note: In dichromatic vision the
spectrum is seen as comprising
only two regions of different HUE
separated by a gray band.
Dichromatic vision can be
subdivided into three types:
PROTANOPIA, DEUTERANOPIA, and
TRITANOPIA.
See Also: PROTANOPIA;
DEUTERANOPIA; and TRITANOPIA.
(1) See DICHROMATIC VISION
(2) The property of varying in
HUE either as the dye
concentration is changed or
as the thickness of the
transmitting sample changes.
The difference between two
compared stimuli (e.g., two colors)
which gives rise (statistically)
to a perceived difference 50% of
the times viewed.
See Also: JUST-NOTICEABLE
DIFFERENCE
DIFFRACTION [4]
A term used in optics to denote
the deviation of rays of light
when such rays pass by the edge of
an opaque body (a nontransparent
object).
Note: As an example, DIFFRACTION
causes the edges of shadows to
appear blurred because the light
rays passing the object are bent
and spread.
A device used to separate a beam
of light into the SPECTRUM COLORS
using the principle of DIFFRACTION.
The device itself contains a
series of fine grooves or wires
which disperse incident light.
The OPTICAL DENSITY measured when
the incident light on the
collection aperture of the
DENSITOMETER is not highly
COLLIMATED and the collection
aperture subtends a large SOLID
ANGLE.
Note: Most densitometers measure
diffuse density.
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DIFFUSED LIGHT [4]
Light which does not reach the
object from a single direction.
Note: Sunlight which has been
scattered by the atmosphere or
clouds is an example of diffused
light. Generally, as diffusion
increases, shadow sharpness
decreases.
The change of the spatial
distribution of a beam of
radiation when it is deviated in
many directions on arrival at a
surface or in traversing a medium.
DIFFUSION CIRCLE [5]
A circle of color in an optical
system caused by rays emanating
from a point source which have
not been brought into sharp
focus because of. CHROMATIC
ABERRATION. A diffusion circle
is likely to show different hues
at different distances from its
center.
DIN [4]
Deutsche Industrie Norm, German
Standards.
The official German color system
in which hue, saturation,
and darkness (the opposite of
lightness) are called FARBTON(T or
F), SATTIGUNG(S), and
DUNKELSTUFE(D), respectively.
There exists a set of color chips,
DIN COLOR SYSTEM (Continued)
each with a set of 3 numbers,
e.g., 3:1:6, which describe the
hue, saturation, and darkness,
respectively.
System of stating emulsion speeds
as laid down by the Deutsche
Industrie Norm (German standards
organization).
DIOPTER [4]
The unit of measure of the
converging or diverging power of
a lens. It is equal to the
reciprocal of the focal length
in meters.
Color matching in a COLORIMETER
for the purpose of numerical
specification of color.
DIRECT LIGHT [5]
Direct light is visible energy
falling straight from its source
upon the eye or upon an object.
DIRECT REFLECTION [5]
Reflection of light without
scatter.
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DIRECTIONAL REFLECTANCE [7]
The amount of light reflected from
a surface in a specified
direction compared to that
reflected in the same direction
from an ideal, nonabsorbing,
perfectly diffusing surface placed
in the same position and similarly
illuminated.
'DISCRIMINATION ELLIPSES
See: MacADAM ELLIPSES
DISPERSION [4]
The separation of a single ray of
white light into a group of
colored rays by a prism or other
optical device.
Note: A Rainbow is an example of
dispersed light.
DISTRIBUTION COEFFICIENTS
(DISTRIBUTION FUNCTIONS) [5]
(Continued)
COORDINATES of the spectral
components of an equal-energy
spectrum. Denoted x, y, z, in
the CIE system and defined in a
table of figures which represents
the characteristics of the
STANDARD OBSERVER.
See Also: COLOR MATCHING
FUNCTIONS
The absolute temperature (in
Kelvin, K) of the BLACKBODY
RADIATOR for which the SPECTRAL
POWER DISTRIBUTION at every
wavelength in the visible spectrum
(-400 to 700 nm) which is
approximately proportional to that
of the source considered.
DISPLACEMENT, ANGLES OF [5]
DOMINANT COLOR
The angles by which the respective
eyes deviate from the direction A term used to describe the
occupied in the primary position. principal color or tone in a
The vertical displacement is the picture.
angle of the eye upward or down-
ward from the primary position; Note: The Dominant Color of a
the lateral displacement is the jungle photograph is green.
angle to right or left.
DISTORTION [4]
Any shift in the position of an
image on a photograph which alters
the perspective or spatial
characteristics of the photograph.
DISTRIBUTION COEFFICIENTS
(DISTRIBUTION FUNCTIONS) [5]
A vision theory stating that
there exists a separate
dominating receptor for the
brightness aspect of vision with
CHROMATIC distinctions introduced
by other receptors modulating the
response of the dominant receptor.
Note: See Table 2 in the
Appendix.
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(1) On the CIE chromaticity
diagram, it is the intersection
of the SPECTRUM LOCUS and the line
drawn through the chromaticities
of the illuminant and the sample
color.
(2) It is analogous to the
concept of HUE.
Note: In Figure 2 in the
Appendix, line A intersects the
Spectrum Locus at 530 nm, thus
530 run is the Dominant Wavelength
of color N.
DRAM [41
A unit of weight in the
avoirdupois system, one-sixteenth
part of an ounce or 27.34 grains.
DUPLICITY THEORY (Continued)
systems present in the retina,
the ROD and the CONE systems,
respectively; the rod-system is
supposed to be responsible for
vision at low or twilight
illumination levels and to yield
an achromatic color; the cone
supposedly mediates daylight and
completes color vision but is
inactive under twilight conditions.
Note: It is currently accepted as
the major theory of vision.
A type of PSEUDO-ISOCHROMATIC
PLATE test of color vision where
colored dot patterns lie on a
background of colored dots.
People with normal color vision
will see the dot patterns
correctly while those with
defective color vision will not see
Generally, Dull colors are the patterns correctly.
desaturated and low in brightness.
DYE
DUNKELSTUFE(D)
In the DIN COLOR SYSTEM, a
logarithmic function of the color's
relative lightness. (Ratio of
luminous reflection of color to
the luminous reflection of the
optimal color having the same
CHROMATICITY.)
A complex chemical, whose
molecules absorb particular
wavelengths; used as a COLORANT
or coloring agent.
Note: In color films, dyes
(CYAN, MAGENTA, and YELLOW) are
created in the emulsion as a
result of the DEVELOPING process.
Note: Literally translated
Dunkelstufe means "darkness DYE COUPLER
degree".
The doctrine that visual sensation
rests upon two distinct receptor
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DYE DENSITY DYE SENSITIZERS
(1) The logarithm to the base 10 Used to sensitize silver halide
of the OPACITY of an area in a emulsions to certain desired
finished dye image. portions of the spectrum.
(2) The density of a dye deposit
is the log10 1 or
Transmittance
log10 1
Reflectance
DYE FORMATION
See CHROMOGENIC DYE FORMATION
DYE GLOBULES
In a processed color positive or
negative these are microscopic
globs of dye which give the image
its color. There are three colors,
CYAN, MAGENTA, and YELLOW, and
mixtures of these globs produce
the entire range of colors. The
globs are visible under high
magnification.
DYE IMPURITIES [5]
Pertaining to the absorption of
light by a dye in regions of the
spectrum where the dye should
transmit completely.
Note: All dyes are impure to some
degree and thus cause some colors
to be unfaithfully produced in the
image.
DYE MORDANTING [5]
In color photography, the treat-
ment of a silver image so as to
replace it in whole or in part
with a substance having an affinity
for dyes.
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EDGE FOG [4]
Fog on film caused by leakage of
light between the flanges of the
spool on which it is wound.
EFFECTIVE APERTURE
See APERTURE, EFFECTIVE
EFFECTIVE TRITANOPIA
See SMALL AREA TRITANOPIA
EFFICIENCY OF A SOURCE OF LIGHT [5]
The efficiency of a source is the
ratio of the total LUMINOUS FLUX
to the total power input. In the
case of an electric lamp it is
expressed in lumens per watt. In
the case of a source depending
upon combustion it may be
expressed in lumens per thermal
unit consumed per unit of time.
The form in which RADIANT ENERGY
travels or is propagated.
The name applied to all
wavelengths of RADIANT ENERGY,
e.g., LIGHT, radio, INFRARED,
ULTRAVIOLET, X-rays, etc.
An optical part constructed of a
simple piece of optical material,
e.g., a lens, prism, or mirror.
EMISSION
The release of RADIANT ENERGY.
EMISSIVITY
The ratio of the RADIANT
EMITTANCE of a source to the
radiant emittance of a BLACKBODY
at the same temperature.
EMITTANCE, SPECTRAL
See SPECTRAL EMITTANCE
EMMERT'S LAW [5]
The perceived size of an AFTER-
IMAGE is directly proportional to
the distance from the observer to
the plane upon which the after-
image is projected.
The sensitive coating on films,
papers, and plates used in photo-
graphy. It consists principally
of a silver salt or salts sus-
pended in gelatin. The emulsion
may be sensitive to the whole
visible spectrum (PANCHROMATIC,
COLOR) or selected portions
(INFRARED, ORTHOCHROMATIC).
EMULSION BATCH NUMBER [4]
A number placed on the label of
film and paper packages which
identifies the batch from which
that particular film or paper was
made.
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EMULSION BATCH NUMBER [4] (Continued) EQUAL ENERGY SOURCE [5]
Note: Variations in film
characteristics can be expected
between batches.
EMULSION SPEED [4]
A light source from which the
amount of energy radiated is
constant for the same wavelength
interval throughout the visible
spectrum.
A property of photographic
emulsions which determines how
long they must be exposed to a
given light source to secure equal
density when developed. This
speed may be given in ASA, DIN,
Weston, Scheiner, or AEI scales.
END EFFECT [6]
EQUAL-ENERGY WHITE [7]
An achromatic light corresponding
to equal radiance per unit of
wavelength at all wavelengths.
EQUIVALENT FOCAL LENGTH
Same as FOCAL LENGTH and measured
to the plane of best average
DEFINITION throughout the angular
field of the optical system.
When a series of color samples
varying only in saturation is See also: FOCAL LENGTH
presented on a neutral background,
the end sample may be perceived EQUIVALENT NEUTRAL DENSITY (END)
more saturated than it really is.
END is defined as the OPTICAL
ENERGY, RADIANT DENSITY that a dye would have if
the necessary amounts of the
See RADIANT ENERGY other fundamental dyes of a
process were added to make it a
ENLARGING [4] neutral gray.
The process of making a print or
negative larger than the original
by projection printing.
Note: Enlarging colored materials
causes colors to become
desaturated.
EQUIVALENT NEUTRAL PRINTING DENSITY
The same as EQUIVALENT NEUTRAL
DENSITY (END) except that a
printing material is used for
visual judgment instead of direct
vision.
The image of the limiting APERTURE
STOP formed in the object space by
all optical elements preceding the
limiting aperture stop.
A type of CHROMATOPSIA or color
vision (usually following over-
exposure to intense light or
prolonged staring at green light)
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ERYTHROPSIA (Continued)
in which all objects appear tinged
with red.
Note: Snow-blindness
EVEN COLOR
Uniformly, the same color over the
surface.
EXCITATION PURITY
The ratio of the distances on a
two-dimensional CHROMATICITY
DIAGRAM from the adopted light
source to the sample color and
from the light source to the color
lying on the SPECTRUM LOCUS or
PURPLE BOUNDARY.
Usually indicated by the word
"PURITY" alone and is similar to
SATURATION.
Note: In Figure 2 in the Appendix
MN is the Excitation Purity of
MP
the color N.
EXHAUSTION [4]
In photography, the state reached
by any processing solution when
the active ingredient is used up.
The image of the limiting APERTURE
STOP in an optical system by all
the lenses following this stop.
Exposure is generally understood to
mean the length of time during
which light is allowed to act on a
sensitive surface. Technically,
it is the product of the
illumination of a unit area of
sensitive surface and the
duration of time through which the
illumination acts.
Note: For colored material
exposure is very critical. Even
slight over- and under-exposure
can affect color balance and
fidelity.
The time interval between the
taking of successive photographs.
The range of exposures that can be
used for acquiring usable
imagery. Determined by the slope
of the CHARACTERISTIC CURVE and
the D-MAX and D-MIN of the film.
Note: In color films the
Exposure Latitude is usually very
small.
EXPOSURE TABLE [4]
A table or set of tables to be
used as a guide in determining
correct photographic exposure.
EXTINCTION COEFFICIENT [5]
The natural logarithm to the base
e of the reciprocal of the trans-
missivity.
The organ of vision which
essentially focuses incoming
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EYE (Continued)
light onto the RETINA where RODS
and CONES are stimulated to begin
the process of transmitting visual
information to the brain.
Note: See Figure 1 in the
Appendix for the structure of the
eye; the parts of the eye are also
discussed in the glossary.
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f-NUMBER [8]
Numerical expression of the rela-
tive aperture of a lens at its
different stops (also the speed of
a lens). The f-number is equal to
the FOCAL LENGTH divided by the
effective diameter of the lens
opening and is written in various
forms, e.g., f8, f/8, 1:8, etc.
A term applied to colors which
have lost their brilliance or
vividness (saturation).
A temperature scale in which the
freezing point of water is
32 degrees and the boiling point
is 212 degrees.
A film whose colors after
processing are intentionally
false compared to the colors of
the scene.
FARBTON (T or F)
In the DIN COLOR SYSTEM it is
analogous to the concept of HUE.
There are 24 Farbtons.
FARNSWORTH DICHOTOMOUS TEST FOR
COLOR BLINDNESS
A test designed to separate color
normals from people with slight
red-green deficiencies from those
who are severely defective. The
test is to arrange 15 Munsell
papers (varying in HUE but not
SATURATION or BRIGHTNESS) in a
certain order. People who are color
normals will arrange according to
HUE, whereas DICHROMATS will arrange
according to the saturation
differences they perceive. The
test allows for a number of people
with light to moderate color
deficiencies to be passed.
A color discrimination test which
can classify those with normal
color vision into superior,
normal, and low color
discrimination ability. It can
also identify TRITANOPIA,
PROTANOPIA, and DEUTERANOPIA but
it should be used only to
corroborate evidence of color
deficiency. The test is to
arrange in a certain order 4 sets
of 25 MUNSELL papers within a
given time limit.
FAST [5]
Will not fade or change in color
on exposure to some named or
implied agency such as light.
FATIGUE, RETINAL [5]
Depletion of the capacity of the
retina to respond to light and
color.
Note: Occurs with prolonged
visual work.
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When an ACHROMATIC light is
flickered at low frequencies
(about 51/sec) CHROMATIC color
sensations may be perceived.
These are known as Fechner's
Colors.
FIDELITY, COLOR
See COLOR FIDELITY
FIDUCIAL MARKS [4]
Index marks (usually four) which
are rigidly connected with the
camera lens through the camera
body and which form images on the
negative and usually define the
principal point of the photograph.
Also, marks (usually four) in
any instrument which define the
axes whose intersection fixes the
principal point of a photograph
and fulfill the requirements of
interior orientation.
FILM BASE [4]
A thin, flexible transparent sheet
of plastic material which is
coated with a light-sensitive
emulsion.
FILM-COLOR [5]
Color seen as soft, non-
substantial, indefinitely
localized, and texture-free as
perceived on a color transparency.
FILM SPEED [4]
That property of film which
determines how much exposure must
be allowed for a given light source
in order to secure a negative of
correct density and contrast.
Any transparent material (GLASS,
GELATIN, or LIQUID) which by
absorption selectively modifies
the light transmitted through it.
Note: Filters may either absorb
wavelengths equally and thus
appear (and called) Neutral Gray;
or they may selectively absorb
certain wavelengths and not others,
thus forming a HUE. For example, a
red filter absorbs (or filters
out) all wavelengths but red
(which it transmits).
Filters may be used for the
following reasons:
(1) To correct the imperfect
color sensitivity of the film
and make it translate the scene
into colors that approximate the
colors that appear to the eye.
Such filters are called CORRECTION
FILTERS.
(2) To distort (brighten or
darken) the reproduction of
certain colors for special
effects. This intentional
distortion is used to enhance
contrast. Filters used in this
way are called Effect Filters or
CONTRAST FILTERS.
(3) To change the SPECTRAL
DISTRIBUTION of the light which
is important in color photography.
Such filters are called Color
Compensating Filters.
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FILTER (Continued)
Note: Various factors must be
considered including light level,
(4) To acquire imagery of a color sensitivity of the film,
single color only; mainly used for and processing times.
scientific and other special
purposes such as telephotography FILTERS, GELATIN [8]
by infrared light. In principle,
most of these filters are extreme The most common camera filters are
cases of the contrast filters thin pieces of dyed gelatin. They
mentioned above. are easiest to make accurately
and offer the widest range of
(5) To remove or cut-off a colors.
portion of the spectrum. Such
Filters are called Cut-off Filters. FILTERS, GELATIN GLASS [8]
FILTER, ANTI-VIGNETTING
See ANTI-VIGNETTING FILTER
FILTER, COLORED [5]
A filter which can modify the
color of a light by selectively
absorbing certain wavelengths and
transmitting others.
FILTER, COLOR IR FILMS
For Color IR films a yellow filter
is used to filter out blue wave-
lengths. A cut-off of 500 to 520
nanometers should be used.
When GELATIN FILTERS have to be
constantly handled they are
usually cemented between glass.
Unless the workmanship of the
cementing is good and the glasses
are absolutely flat and parallel,
the presence of the glass may
upset the optical properties of
the lens. The best filters for
high-quality scientific work are
prepared as optical flats of
guaranteed accuracy. For most
normal photography where such
precision is not needed, the
gelatin is usually cemented
between flat and polished plate
glass.
FILTERS, COLOR SEPARATION
Filters used to obtain COLOR
SEPARATION NEGATIVES. They are
usually wide-band red, blue, or
green filters.
FILTER FACTOR [4]
A number indicating the exposure
increase necessary when using a
filter as compared to the
exposure necessary under the same
conditions without the filter.
FILTERS, GLASS [8]
The better filters are made from
colored glass. Such filters
consist of glass only. While
they are not so easily damaged as
gelatin filters, the range of
colors in which they can be
manufactured is more limited.
Used to reduce the effects of
ATMOSPHERIC SCATTERING, they
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FILTERS, HAZE (Continued)
reduce or cut off blue
wavelengths. Often called MINUS-
BLUE filters. Usually, a filter
that does not transmit below 400
nm is used for medium haze and a
filter that does not transmit
below 420 nm is used for haze at
about 12,000 feet. The filters
used at extreme altitudes cut off
at 450 to 500 nm. However, above
450 run one can expect strong
degree of absorption, while the
choice of substance gives the
necessary absorption
characteristics. The main
advantage of liquid filters is the
exact reproducibility of
characteristics. These depend on
variables which are easily
controlled with great precision:
namely cell thickness and the
composition and strength of the
solutions used.
shifts in color balance toward the FILTER, NEUTRAL DENSITY [4]
yellow.
A deep red filter which absorbs
almost all visible light but
passes the infrared rays. It
should only be used with infrared
film.
See also: BLACK AND WHITE INFRA-
RED FILM
A filter which transmits very
narrow spectral regions as a
result of interfering with the
transmission of other wavelengths.
FILTERS, LIQUID [8]
For specific work special filters
may be required which are not
obtainable or practical with
normal ready-made gelatin or glass
filters. It is often more
convenient to use solutions of
certain colored chemicals in
suitable glass cells. The
thickness of the cell (i.e., the
thickness of solution placed in the
path of the light) determines the
A filter which absorbs and
transmits wavelengths of light
equally and is gray in color.
Note: These filters can be
combined (stacked) to provide a
wide range of densities.
FILTER OVERLAP [5]
The spectral region in which two
or more given filters transmit
light.
FILTER RATIO [4]
The ratio between the exposure
required to produce the same
density on a film when different
filters are used.
FILTERS, ULTRA-VIOLET (UV) [4]
A filter which absorbs the ultra-
violet rays but allows all
visible light to pass; hence, no
increase in exposure time is
required when using this filter.
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FIX [4]
To render a developed photographic
image permanent by removing the
unaffected light-sensitive
material.
A solution which dissolves soluble
silver salts from the emulsion
leaving a dye image.
FIXING [11]
The removal of any sensitive
substance not acted upon by light
or by the developer, thus
rendering the emulsion or print
unalterable by further action of
light.
FLARE [4]
Non-image light which reaches the
photographic emulsion during
camera exposures. Its source may
be any stray light falling directly
on or reflected to the lens or
internal lens reflections of image
light. Its general effect is to
lower the contrast of the image
obtained.
FLAT [5]
A picture or scene which contains
little contrast, i.e., the same
lightness or darkness or grayness.
FLICKER PHOTOMETRY [5]
A method of PHOTOMETRY in which
two different color stimuli are
alternately presented to the eye
at a suitable rate; the stimuli
are considered equal in luminance
when the flicker is minimum.
FLIGHT OF COLORS [5]
The succession of color
perceptions which follows an
intense momentary light stimulus
viewed against a dark ground.
FLUORESCENCE [5]
(1) The process by which a
material absorbs RADIANT ENERGY
and re-emits it in the form of
radiant energy of a different
wavelength band, all or most of
whose wavelengths exceed that of
the absorbed energy.
(2) The re-emitted radiant
energy.
Note: Fluorescence, as
distinguished from
PHOSPHORESCENCE, does not persist
for an appreciable time after the
end of the excitation process.
A fluorescent lamp is an electric
discharge lamp in which the
RADIANT ENERGY from the electric
discharge is transferred by
suitable materials (phosphors)
into wavelengths giving higher
LUMINOSITY.
Note: See Figure below for
spectral distribution of a
"DAYLIGHT" Fluorescent Lamp.
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FLUORESCENT LAMP (Continued)
Wavelengths, nm
FLUX
Rate of transfer of energy
See Also: RADIANT FLUX; LUMINOUS
FLUX
FOCAL LENGTH [4]
The distance measured along the
optical axis from the optical
center (rear NODAL POINT) of the
lens to the plane of critical
focus on a very distant object.
Note: See Figure below; F is the
focal length.
HF-H
FOCAL PLANE [8]
Imaginary plane on which a lens
forms a sharp image when correctly
focused. For sharp pictures the
emulsion surface of the plate or
film in a camera must be
accurately positioned in the
focal plane of the lens.
FOCAL POINT (PRINCIPAL FOCUS) [8]
Point of intersection of all rays
of light transmitted by a lens
from a given object point. When
the object is at infinity and the
incident rays are parallel to the
lens axis, the image is the
Principal Focal Point and lies on
the axis of the lens.
Note: See Figure below.
FOCUS [4]
Principal
Focal Point
(1) The point at which the rays
from a point source of light
reunite'and cross after passing
through a camera lens. In
practice, the plane in which a
sharp image of any scene is
formed.
(2) To make adjustments to have
the FOCAL PLANE and the emulsion
layer coincide.
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FOG [4]
(1) A fault in a negative seen as
a veil over the whole negative
either as darkened patches or as
an obscuring of shadows (light
areas in the negatives). It may
be due to light accidentally
reaching the negative .(light fog),
to an error in compounding or
using solutions, or to gradual
degeneration of the film or
developer with age.
(2) A mist composed of water-
vapor particles which may also
contain dust and smoke.
FOOT-CANDLE [8]
A unit of ILLUMINANCE representing
the light intensity over a surface
one foot away from a standard
CANDLE. It is equal to 1 LUMEN
per square foot (1 lumen/ft2) or
1.0764 x 10-3 LUX.
Note: See Table 1 in the
Appendix.
See Also: LUMEN, LUX.
FOOT-LAMBERT
A unit of LUMINANCE equal to
1 candela/ft2. It is also equal
Tr
to 1.0764 millilamberts, or
3.4263 candela/m2.
Note: See Table 1 in the
Appendix.
See Also: LAMBERT; METER-LAMBERT
A quick color vision test for
normalcy of yellow-blue and
red-green vision.
FOVEA (FOVEA CENTRALIS) [5]
A small ellipse-shaped depression
in the central region of the
RETINA which measures somewhat
less than a degree of visual angle
at its maximum diameter and is
characterized by the sharpest
CONE vision.
Note: The Fovea is the center for
visual fixation and attention and
is practically 100% CONES. See
Figure 2 in the Appendix.
FOVEAL CONES
Cones lying in the FOVEA.
FREEMAN ILLUMINANT-STABLE COLOR
VISION TEST
A PSEUDO-ISOCHROMATIC test which
separates color normals from red-
green deficiencies. This test
gives comparable results under
several types of illuminants
(COLOR TEMPERATURE of 2,000 K to
4,000 K). However, some dot
patterns may be unfamiliar to
many people who take the test.
FRINGE (RAINBOW EFFECT)
A defect of a color picture where
edges are multicolored resulting
from lack of registration of the
component images. A fringe may be
caused by parallax, error in
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FRINGE (RAINBOW EFFECT) (Continued)
printing registration, or by
movements of the object between
the exposure or COLOR-SEPARATION
NEGATIVES or ADDITIVE COLOR
SEPARATIONS.
FULL APERTURE [4]
The maximum opening of a lens or
lens diaphragm.
In the OSTWALD COLOR SYSTEM it
describes the maximum saturation
of a HUE. Color Content is the
dimension analogous to SATURATION.
The set of three spectral
sensitivity or mixture curves (one
each for red, blue, and green
sensitivities), usually plotted
with relative luminosity as a
function of wavelength, which
represent the actual sensitivities
of the fundamental retinal
response processes, according to
tri-receptor theories of color
vision. The maxima of these
response curves are believed to be
450, 540, and 590 nanometers,
respectively.
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GAMMA [4]
A numerical designation for the
CONTRAST of a photographic
material as represented by the
slope of the STRAIGHT-LINE portion
GELATIN [4]
A transparent colloid which swells
to a jelly-like mass in cold
water but dissolves in hot water.
Used as a medium for the silver
salts in coating plates, films,
and sensitized papers.
GELATIN FILTERS [5]
A filter in which gelatin is used
as the vehicle for the absorbing
material.
lightness range in the negative is
one-half of the lightness range in GENERAL COLOR [5]
the scene.
of the CHARACTERISTIC CURVE.
Gamma is numerically equal to the
tangent of the angle which the
straight-line portion makes with
the base line. A gamma of 1 in a
negative signifies that the
lightness range in the negative
is the same as the range of light
values in the scene photographed;
a gamma of .5 signifies that the
A term applied to the tonality of
See Also: CHARACTERISTIC CURVE a whole image.
GANGLION CELLS [4] Note: The general color of a
jungle image is green.
The second layer of nerves leading
away from the RODS and CONES which GENICULATE BODIES, LATERAL
are activated by the BIPOLAR
CELLS. Their axions pass across
the inner retina and out of the
eyeball to form the OPTIC NERVE.
GAP [4]
A pair of tissue bodies lying
within the thalamus (portion of
the brain) where the OPTIC NERVE
connects with the OPTIC
RADIATIONS.
Any space where aerial photographs GEOMETRIC METAMERISM
fail to meet minimum coverage
requirements. This may be a space
GLARE [5]
not obtained. The disturbance of the
sensitivity of the eye
experienced when portions of the
field of view have a brightness
not covered by any photograph or
a space where the minimum
specified overlap or sidelap was
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GLARE [5] (Continued)
or intensity greatly in excess of
that of the average.
Note: Glare, as such, does not
occur on images or prints, although
one can identify glare from objects
in the scene.
Translucent dye particles in
colored transparencies.
GLOSS [5]
The light reflected from_the
fullest black on a glazed print is
of the order of 1-2 percent of the
incident light, while on a matt
print it is around 5-10 percent.
Assuming a maximum reflectivity of
80-90 percent from the pure white
paper, the brightness range of a
glossy print can be as high as
50 : 1 and of a matt print about
15 : 1 or 10 : 1.
The increased brightness range is
important in copying or photo-
mechanical reproduction and it
explains why prints on glossy
paper always reproduce best.
The glossy surface has its dis-
Property of a surface which reflects advantages: it shows up detail;
a substantial proportion of the and it tends to emphasize grain-
incident light in a mirror direction iness, scratches, and other
which is responsible for its shiny blemishes. Underexposed shadow
or lustrous appearance. areas show up as featureless black
patches on glossy paper.
GLOSSY PAPER [8]
GODLOVE SMALL-COLOR-DIFFERENCE
Photographic printing paper with FORMULA
a smooth shiny surface that can be
further emphasized by glazing. A formula used to compute color
Note: A glossy surface is devoid
of surface texture and is thus
invisible-- like the surface of a
polished mirror. It therefore
shows up all the detail in the
photograph. Since the smooth sur-
face does not scatter light, a
glossy print is better than a
rough surface print because it
shows brighter colors, is able to
cover a greater brightness range,
and can reproduce shadow detail
better.
differences from differences in
the MUNSELL HUE, VALUE, and CHROMA
of the two colors being compared.
GONIOPHOTOMETER [5]
A device that measures
directional reflectance and
directional transmittance of a
surface with collection of light
confined to a narrow range of
angles, the central ray of which
is variable over a wide range of
angles relative to the surface of
the test specimen.
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GOST SPEED [8]
Film speed rating in use in the
(1) One of the discrete
silver
Soviet Union and some eastern
particles resulting from
the
European countries. GOST speeds
development of an exposed
light-
are quoted on an arithmetical
sensitive material.
scale and are fairly similar to
the ASA arithmetical speed numbers.
The GOST Speed criterion is based
on the exposure point
corresponding to a specified
minimum density above base plus
fog of the film.
(2) This term may also be used
with color images, although the
grain is really a DYE GLOBULE.
Note: Grains have definite edges
where globules are translucent
and, thus, appear different under
high magnification.
Term referring to the TONE scale GRAININESS (GRAINY)
The mealy appearance of the image
caused by the clumping together
of the silver grains or, in color
transparencies, the clumping
together of the GLOBULES.
between the extreme dark and light GRAM (METRIC SYSTEM) [4]
tones, it is said to have a Hard
Gradation. The international unit of weight.
or CONTRAST range of a developed
image. An image which shows a
large number of intermediate tones
of gray between the extreme dark
and light tones is said to have a
Soft Gradation; if there are only
a few recognizable shades of gray
Note: The Gradation of an emulsion
is at once obvious from the
steepness of its CHARACTERISTIC
CURVE(S). An emulsion with a
steep curve(s) will possess a
harder gradation than one with a
shallow curve(s).
GRADIENT [4]
Applied to the CHARACTERISTIC
CURVE, the slope of any chosen
part of the curve; distinguished
from GAMMA which refers to the
slope of the STRAIGHT-LINE portion
of the curve only.
It is the weight of a cubic centi-
meter of pure water at its
maximum density. It is equal to
15.432 grains AVOIRDUPOIS.
A term referring to the granular
structure of the sensitive
emulsion as represented by the
measured variation in the
distribution of an apparently
uniform silver or DYE GLOBULE
deposit.
Note: It is a scientific concept
whereas GRAININESS is a
subjective visual impression
created by the granular structure
of a photographed material.
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GRASSMANN'S LAWS (2) Any hue predominantly
similar to GREEN.
The laws of ADDITIVE COLOR MIXTURE
as stated by Grassmann in 1855 and
serving as a basis for the science
of COLORIMETRY. Of these laws the
(3) The complement of MAGENTA or
PURPLE.
most important are (a) lights of GREEN-BLINDNESS
the same color produce identical
effects in mixtures regardless of
their spectral composition; (b)
two lights of the same color,
added to two other lights of the
same color, produce mixtures that
likewise have the same colors ;
(c) two lights of the same color,
each subtracted respectively from
mixtures of equal color, leave
remainders that color-match; and,
(d) if one component of a two-
component mixture is steadily
changed (while the other remains
constant), the color of the mixture
See DEUTERANOPIA
GREEN FILM [4]
Newly developed film which,
although apparently dry, still
contains a considerable amount of
moisture. Even in a warm room
film does not become completely
dry in less than 6 to 12 hours,
and it is best not to attempt
printing or enlargement of film
sooner than this.
steadily changes. GROUND [5]
GRAY [5]
(1) The focused or unfocused
surroundings of a figure or
An ACHROMATIC COLOR of any light- object perceived as lying beyond'
ness intermediate between the and not belonging to the figure
extremes of black and white. or object.
GRAY SCALE [4] (2) The earth as seen on high-
altitude imagery.
A series of ACHROMATIC COLORS
ranging from white to black with
intermediate tones of gray.
See Also: STEP WEDGE; WEDGE
GREEN [5]
(1) The hue attribute of visual
sensations typically evoked by
stimulation of the approximately
normal retina with radiation of
wavelength 513 nm.
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H. & D. CURVE [4]
(1) A Hurter and Driffield graph
showing the relationship of
exposure and density where the
density is plotted against the
logarithm of the exposure.
(2) See CHARACTERISTIC CURVE
HALATION[4]
development. It is used after
DEVELOPMENT and before FIXING.
HARDNESS [4]
In negatives and prints too much
Contrast; too great a difference
between lights and shadows; too
steep a GRADATION.
HARDY-RAND-RITTLER PSEUDO-
ISOCHROMATIC PLATE TEST
A fault of film in which the high-
lights are blurred and encroach
upon the surrounding shadows. It
is caused by the scattering of
light by the silver halide
crystals and by the reflection of
the film on the back of the camera
platen.
Note: On color films, bright
colors of highlight areas may
appear smeared.
HARDENING BATH (HARDENER)
A solution used to harden the
gelatin on the emulsion.
HARDENING FIXER [8]
Fixing bath, particularly one for
fixing negatives, that contains a
hardener so that the emulsion is
hardened and rendered less liable
to injury in subsequent washing,
drying, and handling.
HARDENING STOP BATH [11]
A HARDENING BATH that also contains
an acid to arrest the progress of
A test to distinguish types and
degrees of red-green and yellow-
blue color deficiencies. It uses
simple designs in colored dots on
colored dot backgrounds and has
been used with children,
foreigners, and illiterates.
The suspension of moisture, dust,
and other matter in the atmosphere
which scatters ultraviolet,
violet, and blue wavelengths of
light. Longer wavelengths of
light, such as red, are less
affected.
Note: Haze causes high-altitude
and oblique color images to have
a bluish overcast, reducing color
fidelity and balance.
See Also: FILTER, HAZE; RAYLIEGH
SCATTERING; MIE SCATTERING
HEIGHTEN [5]
To heighten a color is to increase
its intensity.
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HERING GRAYS [5]
A set of 50 neutral gray papers
graded from extreme white to
extreme black in steps which
approximate subjective equality.
The set represents the ACHROMATIC
series of colors.
HERING THEORY OF VISION [5]
The theory proposed by E. Hering
and modified by later writers,
according to which colors are due
to three pairs of antagonistic
processes in the optic system, one
member of each pair being
destructive, the other construc-
tive, the pairs yielding
respectively, white and black,
yellow and blue, and red and
green. Thus we see yellowish and
bluish colors but not both at the
same time (yellow cancels blue and
vice-versa). Similarly we see
reddish and greenish colors but
never both at the same time (red
cancels green and vice versa), etc.
Note: This theory predicts a form
of yellow-blue blindness
(TETARANOPIA) of which no uncom-
plicated case has ever been
reported. Yet it fails to predict
Measurement of the intensity of
colored light sources using a
PHOTOMETER.
HETEROCHROMIC [5]
Same as DICHROMATISM (definition
2) but can apply to samples having
more than two shades as a function
of change in concentration.
HIGHLIGHTS [4]
The densest parts of a negative
and the lightest parts of a print
or positive transparency.
A test to separate color normals
from green-red defectives which
involves the matching of skeins
of different-colored yarn with
three standard skeins (red, green-
yellow, and purple).
Note: The test has not been
standardized in terms of the
skein colors and detects only
about half the color defectives
examined [6].
two of the chief types of HOMOCHROMATIC
DICHROMATIC VISION (PROTANOPIA and
TRITANOPIA). See Table 2 in the
Appendix.
A color of single HUE and
SATURATION but can vary in
BRIGHTNESS.
See Also: HURVICH-JAMESON
QUANTITATIVE OPPONENT COLORS THEORY HOMOCHROMATIC AFTER-IMAGE [11]
HETEROCHROMATIC See AFTER-IMAGE, POSITIVE
Colors which vary in both HUE and
SATURATION.
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HORNER'S LAW [5]
A principle of the inheritance of
color-blindness according to which
the common types are transmitted
from males to males through
unaffected females (via a sex-
linked recessive gene).
HUE [4]
(1) That attribute of a CHROMATIC
COLOR by virtue of which it
differs from gray of the same
lightness and which allows it to
be classed as red, yellow, green,
blue, or intermediate mixes of
these SPECTRAL COLORS.
(2) A dimension in the MUNSELL
COLOR SYSTEM of uniform perceptual
steps in hue.
(3) Analogous to DOMINANT WAVE-
LENGTH.
HUE THRESHOLD, DIFFERENTIAL
The just-perceived wavelength
difference in Hues at constant
purity and luminance (saturation
and brightness) expressed in
nanometers.
Note: Generally, .1 to .2 nm are
required over most of the spectrum
but up to .6 nm at the extremes.
See the Figure below:
500 550 ?00 650
/nm
Differential color sensitivity
throughout the spectrum, according
to Wright and Pitt. Wright's
colorimeter, free from diffused
light, 2? field, average retinal
illumination 70 trolands except in
the extreme blue, method of limits.
From LeGrand, Yves, Light, Colour
and Vision, Fig. 73, p. 275.
(Translated by R.W.G. Hunt,
J.W.T. Walsh, and F.R.W. Hunt,
New York; John Wiley & Sons, Inc.,
1957.)
HURVICH-JAMESON QUANTITATIVE
OPPONENT COLORS THEORY
A quantitative expression of the
HERING THEORY OF VISION which has
been the most successful in
explaining quantitatively
recorded facts of color vision.
Note: The criticisms of it are
the same as the HERING THEORY OF
VISION (which see). See Table 2
in the Appendix.
HYPERFOCAL DISTANCE [4]
If an object at a great distance
(infinity) can be sharply
focused, it is found that, without'
altering the position of the lens,.
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HYPERFOCAL DISTANCE [4]
a comparatively near object is
still "in focus"; that is, it is
rendered without perceptible
unsharpness. The distance to this
near point is the hyperfocal
distance.
HYPERSENSITIZING [4]
A term applied to various methods
of increasing the sensitivity and
SPEED of an unexposed emulsion;
for example, fuming or bathing with
ammonia, fuming with mercury, etc.
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ICI [5]
Abbreviation for the International
Commission on Illumination.
Note: The French title of the
ICI, Commission Internationale de
1'Eclairage, and its abbreviation
CIE is commonly used but rarely
the German title (Internationale
Beleuchtungs-Kommission) or its
abbreviation IBK.
The light being sensed or
perceived by the visual system
when there is no external source
of light. Caused by the
continuous physiological activity
of the visual system.
ILLUMINANCE [5]
LUMINOUS FLUX incident per unit
area of surface.
Note: This quantity has commonly
been called illumination in the
past. Usual units are the LUX or
LUMENS per square meter. See
Figure 4 in the Appendix.
In the CIE system, light defined
by its SPECTRAL POWER DISTRIBUTION,
in contrast to a source, which is
a physically realizable object
emitting RADIANT POWER.
ILLUMINANT COLOR [5]
Color seen as glowing, luminous,
or belonging.to light source,
e.g., a colored light bulb.
ILLUMINANT-COLOR PERCEPTION [5]
Color perceived as belonging to a
source of light.
ILLUMINANT, STANDARD
See STANDARD ILLUMINANT
ILLUMINATION
See ILLUMINANCE
ILLUMINATION COLOR [5]
Color seen as belonging to
illumination distributed in space,
e.g., color of sunlight in a room,
red light flooding a stage, etc.
ILLUMINATION-COLOR PERCEPTION [5]
The principle that the ILLUMINANCE
of a surface varies directly as
the INTENSITY of the light source,
inversely as the square of its
The awareness of the distribution
of colored light in space.
distance, and directly as the IMAGE
cosine of the angle made by the
light-rays with the perpendicular
to the surface.
The counterpart of a scene
produced on film by the reflection
See Also: INVERSE SQUARE LAW
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IMAGE (Continued)
or refraction of light when
focused by alens or mirror.
IMAGE, LATENT
The emission of light from a
heated solid or liquid. Its
SPECTRAL DISTRIBUTION or color is
dependent on its temperature,
e.g., a tungsten filament lamp.
An invisible image on exposed but
undeveloped film or print that can INCANDESCENT TUNGSTEN LIGHT
be revealed by DEVELOPMENT.
IMAGE-MOTION COMPENSATOR (I.M.C.)
[4l
A device installed with certain
aerial cameras to compensate for
the forward motion of an aircraft
while photographing ground objects.
True image-motion compensation
must be introduced after the camera
is oriented to the flight track of
the aircraft and the camera is
fully stabilized.
IMAGE, RETINAL
The optical image of an external
scene focused upon the RETINA by
the refracting surface (lens) of
the eye.
IMBIBITION [5]
(1) A process for producing a
dye-image by mechanical printing.
A dyed relief or differentially
tanned matrix of some substance
such as gelatin is brought into
intimate contact with a moist
absorbing layer, the dye diffusing
from the matrix to the absorbing
layer.
(2) To absorb or assimilate
moisture, gas, light, etc.
Light emitted by a tungsten
filament. Wavelength/relative
power distribution varies with
temperature of the filament.
Note: In the Figure below are
spectral power distribution
curves for (a) 25-Watt, (b) 50-
Watt, (c) 500-Watt, and (d) 1000-
Watt lamps.
Of I
0L L
400 500 600 700
Wavelength (nm)
INCIDENCE, ANGLE OF [5]
The angle between the path of an
oncoming ray of light and the
normal to the surface on which it
impinges.
Note: Angle A is angle of
incidence.
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INCIDENCE, ANGLE OF [5] (Continued) INDUCED COLOR
See Also: SNELL'S LAW
INCIDENT FLUX
The rate at which radiant energy
strikes a surface.
INCOMPLETE RADIATOR
A RADIATOR that emits less power
than a BLACKBODY at the same
temperature.
INDEX OF REFRACTION
See REFRACTIVE INDEX
INDIRECT COLORIMETRY
The measurement of a color using
indirect means.
Note: The color of a nonself-
luminous object can be computed
A color or change in color which
appears in a given portion of the
subjective visual field not caused
by direct stimulation of the cor-
responding portion of the retina,
but caused by the stimulation of
the surrounding retina.
Note: Colors as perceived may be
affected by adjacent colors. For
example, yellow will appear
darker in a black surround than
in a gray surround. The darker
yellow is the Induced Color.
See Also: SIMULTANEOUS COLOR
CONTRAST
The color which affects the per-
ceived appearance of an adjacent
color.
Note: Distinguished from INDUCED
COLOR, the color that causes the
effect.
from its SPECTRAL REFLECTANCE (or INFINITY [4]
transmittance), the SPECTRAL POWER
DISTRIBUTION of the illuminant,
and the CIE COLOR MATCHING
FUNCTIONS for the spectrum. These
calculations consist of summing
the products of these three groups
of data, wavelength by wavelength
one complete calculation for each
of the three PRIMARIES.
In photography, an indefinitely
great distance; a distance so
great that rays from a point
source of light at that distance
are parallel for all practical
purposes. For most lenses and
most types of work, any distance
1,000 times the focal length may
be safely regarded as infinity.
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Term sometimes used to describe
emulsions sensitive to infrared
radiations, as used for infrared
photography.
IR
Abbreviation for "INFRARED".
INFRARED (IR)
Pertaining to or designating the
portion of the electromagnetic
spectrum with wavelengths just
beyond the red end of the visible
spectrum, such as radiation
emitted by a hot body. Their
wavelengths are longer than those
of visible light and shorter than
those of radio waves. Light rays
whose wavelength is greater than
700 nanometers. Invisible to the
eye, infrared rays are detected
by their thermal and photographic
effects.
Note: There are films which are
sensitive to the IR wavelengths
which image in black and white
and FALSE-COLOR. These films
generally image live vegetation as
a particular shade of color such
that living vegetation can be
detected easier and be distin-
guished from most other targets
and backgrounds.
See Also: COLOR INFRARED FILM;
BLACK AND WHITE INFRARED FILM
The use of an instrument to
determine the CIE TRISTIMULUS
VALUES X, Y, AND Z for a given
transparency or opaque sample.
The two most frequently used
instruments are the RECORDING
SPECTROPHOTOMETER and the
TRISTIMULUS COLORIMETER.
See METAMERISM, INSTRUMENTAL;
METAMERISM, GEOMETRIC
INTEGRAL DENSITOMETRY (INTEGRAL
DENSITIES)
The measurement of integral
densities. They are the result
of the combined or net effect of
the superimposed dyes in a color
film with no attempt to separate
the effects of a single dye from
the total density. Four types of
integral densities are commonly
used: INTEGRAL SPECTRAL DENSITIES,
PRINTING DENSITIES, COLORIMETRIC
DENSITIES, and ARBITRARY THREE-
FILTER DENSITIES.
See Also: (See above four
densities)
INTEGRAL DENSITIES measured by a
DENSITOMETER whose response
approximates the photographic
response of the printing or
duplicating material. These may
also be calculated mathematically
by using equations which take into
account the characteristics of the
duplicating material.
The density measured, wavelength-
by-wavelength, on all the
fundamental dyes in a material.
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INTEGRAL SPECTRAL DENSITIES (Cont'd) INTER-IMAGE EFFECTS
A SPECTROPHOTOMETER or similar
device capable of narrow-band,
wavelength separations is required.
An optical device used in a
SPECTROPHOTOMETER to collect
light reflected from an opaque
sample.
INTENSITY, OF LIGHT
The amount of RADIANT ENERGY per
unit area. The higher the amount,
the greater the intensity.
The interaction, during processing,
of the chemical reactions that are
occuring in each of the emulsion
layers of a multilayer film. For
example, the chemical reaction that
develops the magenta image may also
cause some undesired development of
the cyan image in the next emulsion
layer.
Note: These interactions are gen-
erally taken into account and used
as beneficial design characteris-
tics.
See Also: ILLUMINANCE; LUMINANCE;
CANDLE POWER.
An effect resulting from the
meeting of two light rays of
identical wavelength but different
phase; when the phase difference
is 1/2 wavelength, the two light
waves cancel and darkness results;
interference between two rays of
HETEROCHROMATIC light results in
colored patterns similar to the
SPECTRUM produced by a PRISM.
INTERFERENCE COLORS 15]
Colors resulting from the destruc-
tion of the light of certain wave-
lengths and the augmentation of
the light of others by INTERFERENCE.
INTERFERENCE FILTER
Reflection of light from the various
glass surfaces of a compound lens.
Such reflection cuts down the illu-
mination passing through the com-
pound lens.
INTERNAL TRANSMITTANCE
See TRANSMITTANCE, INTERNAL
INTERNAL TRANSMISSION FACTOR [5]
The ratio of the LUMINOUS FLUX
reaching the second surface of a
transparent body to the luminous
flux leaving the first surface.
Note: In the Figure below, the
ratio of the flux at A to that at
B.
A
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An international unit of light
intensity (see CANDELA).
INTERPUPILLARY DISTANCE (INTEROCULAR
DISTANCE) [12]
The distance between the pupils of
the eye of an individual. The
range is from 2.2 to 3.0 inches.
INTERVALOMETER [4]
A device used on aerial cameras
which automatically operates the
shutter at predetermined intervals.
INVARIABLE HUES [6]
INVERSE SQUARE LAW [4]
The illuminance of a unit surface
and, consequently, the brightness
of the surface vary inversely with
the square of the distance from a
point of light source.
See Also: ILLUMINANCE, LAW OF
IRIDESCENT [5]
Changing color with position.
Usually applied to colors produced
by INTERFERENCE, REFRACTION, or
DIFFRACTION.
Note: Such as the rainbow of
colors on a soap bubble or on an
oil film on water.
Certain wavelengths produce hues
which do not change as far out on IRIS
the retina as saturation is
elicited. These wavelengths are A part of the CILIARY BODY which
approximately 464 nm, 489 nm, and has a central circular aperture
571 nm. called the PUPIL which is the
APERTURE STOP of the eye.
Note: See Figure 1 in the Appendix.
The Invariant Hues are those which
are independent of the BEZOLD- IRIS DIAPHRAGM [4]
BRUCKE phenomenon, i.e., those hues
which do not change with a change A lens control composed of a series
in luminance of the stimulus. of overlapping leaves operated by
In general, the HUES correspond to a revolving ring to vary the
the following wavelengths: 474 nm aperture of the lens.
(blue), 506 nm (green), 571 nm
(yellow), and a complementary IRRADIANCE
wavelength of 495 nm (red).
The RADIANT FLUX incident per unit
See Also: BEZOLD-BRUCKE PHENOMENON area of a surface.
INVARIANT MATCH IRRADIANCE, SPECTRAL
A COLOR MATCH which is agreed upon The RADIANT FLUX per unit wave=
by all people under all illuminants. length incident on a unit area
of surface.
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(1) The spreading of light in an
emulsion caused by reflection from
the surfaces of the silver halide
crystals. The slight blurring
caused by irradiation should not
be confused with the more notice-
able and extensive blurring known
as HALATION which is caused by
reflection from the back surface
of the plate or film on which the
emulsion is supported.
(2) The perceived spreading of
brighter colors onto their darker
surround which may slightly
enlarge the perceived size of the
brighter color.
ISCC-NBS(INTER-SOCIETY COLOR COUNCIL-
NATIONAL BUREAU OF STANDARDS) COLOR
DESIGNATION
Designation of a color by simple
English words according to a method
devised by the Inter-Society Color
Council and worked out in detail
at the National Bureau of Standards.
The 267 color names used include a
number of hue names plus the
adjectives light, medium, dark,
pale, grayish, blackish, moderate,
brilliant, strong, deep, and vivid.
These color names are related to
specific regions in the MUNSELL
COLOR SYSTEM.
(3) The process by which radiant A test to distinguish green-red
energy is made to be incident upol color deficiency from normal color
a surface. vision. It is a PSEUDO-
ISCC (INTER-SOCIETY COLOR COUNCIL)
COLOR APTITUDE TEST
ISOCHROMATIC PLATE color test.
ISOCHROMATIC [4]
A test used to measure the abilit~ Of equal color.
to discriminate saturation dif-
ferences and scored according to ISOMERIC COLORS
the accuracy of saturation matche .
Colors whose SPECTRAL DISTRIBUTIONS
are the same and have identical
TRISTIMULUS VALUES X, Y, and Z.
Not a recommended term.
drawn from an identical set of 48 ISOMERIC PAIR
The examinee is instructed to
match on a panel of 48 colored
chips (involving 4 HUES, each wits
a set of chips varying in
SATURATION) a colored chip he has
colors. People can be sorted into
five groups according to satura-
tion discrimination: low, satisf c-
tory, good, excellent, and
exceptional.
Two colors of identical SPECTRAL
DISTRIBUTIONS and TRISTIMULUS
VALUES X, Y, and Z. Not a
recommended term.
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ISOPAQUE CURVE [51
A line connecting a series of
points of equal opacity. Such
curves when applied to spectrograms
may be used to demonstrate the
color sensitivity of photographic
materials.
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JUST-NOTICEABLE DIFFERENCE
(JUST-PERCEPTIBLE DIFFERENCE) [5]
The least difference in value
between two compared stimuli
which (in a given individual) gives
rise to two different sensations
50% of the times presented.
Abbreviated j.n.d.
Note: For example the j.n.d. of
two spectral green colors is about
1 to 2 nanometers.
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KELVIN (K)
A temperature scale starting at
absolute zero (approximately
-273 C) and having a degree of the
same magnitude as those of the
CELSIUS scale. Thus 0 C = 273 K;
100 C = 373 K. According to con-
vention, the degree sign and the
word degree are now omitted in all
references to Kelvin temperatures.
See Also: ABSOLUTE TEMPERATURE
KILOWATT
1,000 watts.
KIRCHOFF'S LAW [5]
Ratio of RADIANT EMITTANCE to
RADIANT ABSORPTANCE is the same
for all surfaces at the same
temperature.
KODACHROME [8]
Pioneer SUBTRACTIVE reversal
process of color photography worked
out by L. D. Mannes and L. Godowsky
and introduced by Kodak in 1935.
It makes use of an integral TRIPACK
in which the emulsions contain no
color formers but are subject
to individual dye development.
KODACOLOR [8]
(2) The name is now applied to
a negative-to-positive process for
making positive color prints.
KODAK [8]
Trade name of USA Eastman Kodak
Co., coined by George Eastman,
founder of the organization, in
1888 and first registered in
Great Britain on May 3, 1888,
then in the United States on
September 4, 1888, and subsequently
in many other countries. It was
first used in connection with
Eastman's original box-type camera.
Eastman was determined to adopt a
trademark that could not be mis-
spelled or mispronounced in any
language, or infringed or copied
by anyone. He wanted a strong
word that could be registered and
that people would not forget.
A two-flux turbid medium theory
for describing the way light
interacts with any medium which
both scatters and absorbs it.
Describes the reflectance and
transmittance of translucent
materials in terms of a scattering
coefficient and an absorption
coefficient K. In the limiting
case of opaque materials,
K
(1-R)2
(1)
Originally an additive method
S __
2R
ith
h
h
d
i
l
of
the
otograp
s w
ng co
or p
pro
uc
aid of a lenticular screen
where R is the reflectance of the
embossed on the front of the film.
It was first made available
commercially in 1928 on 16 mm.
cine film.
sample. For colored samples
where R, K, and S depend upon the
wavelength, the Kubelka-Munk
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KUBELKA-MUNK ANALYSIS (Continued)
Analysis can be used to formulate
the mixture of colorants (dyes
or pigments) to produce a specified
color. Works well for paints,
plastics, paper textiles, and many
other systems.
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LADD-FRANKLIN THEORY OF COLOR
VISION [5]
LATERAL GENICULATE BODY
A theory which assumes that in the
retinal nerve endings the respec- See GENICULATE BODIES, LATERAL
tive light stimuli liberate red-,
green-, and blue-stimulating LATERAL-OBLIQUE PHOTOGRAPH [12]
substances from a complex photo-
sensitive molecule and that red An oblique aerial photograph taken
and green, when present, unite to with the camera axis as nearly
form a yellow-stimulating sub- normal as possible to the flight
stance. According to this theory, line.
blue and green, or blue and red
cannot unite so, and do not LATITUDE
individually disappear in the
respective blue-green and blue- See EXPOSURE LATITUDE
red (or purple) mixtures. All
colors are produced by various mix- LEADER [12]
tures of these liberated substances.
A strip of material at the
Note: See Table 2 in the Appendix. beginning of a roll of film which
is used to assist the threading
of the film through the camera
and processing equipment.
The lambert is a unit of surface
LUMINANCE equal to 1/'r candela per LENS
.square centimeter.
Note: See Table 1 in the Appendix.
See Also: FOOT-LAMBERT; METER-
LAMBERT
LATENT IMAGE
See IMAGE, LATENT
LATERAL-CHROMATIC ABERRATION [4]
A lens aberration which affects
the sharpness of images off the
OPTICAL AXIS because different
colors undergo different
magnifications.
(1) A transparent object (usually
made of glass, fluorite, or
quartz) having two polished
surfaces of which at least one
is curved. It is shaped so that
the rays of light when passing
through it are made to converge
or diverge.
(2) See CRYSTALLINE LENS
LENS ELEMENT [12]
One lens of a complex lens
system. In a photographic lens,
the terms front element and rear
element are often used.
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LEUCO-BASE See Also: ADAPTATION, LIGHT;
PHOTOPIC VISION
A white or slightly colored sub-
stance which upon oxidation LIGHT WAVES
(sometimes accompanied by reaction
with an acid or base) yields a Light when regarded as an
more highly colored dye. undulatory or wave-like phenomenon.
LIGHT [1] LIGHTNESS
(1) The aspect of RADIANT ENERGY
or the portion of the ELECTRO-
MAGNETIC SPECTRUM of which a human
observer is aware through the
visual sensations that arise from
the stimulation of the RETINA of
the eye.
(2) Used in reference to colors
having brightness values near
white, such as light red, light
blue, etc.
(3) Diffusely reflecting a
relatively large amount of the
incident light.
(4) The opposite of dark.
LIGHT ADAPTATION
See ADAPTATION, LIGHT
LIGHT-ADAPTED EYE [5]
(1) The attribute which permits
a surface color (CHROMATIC or
ACHROMATIC) to be classified as
equivalent to some member of the
series of grays ranging from
black to white.
(2) The attribute of color
perception by means of which
an object is judged to reflect
light rather than another object.
LIMEN
Same as THRESHOLD
See Also: DIFFERENCE LIMEN
LINE PAIR
In resolution targets, the width
of one line and one space in a
parallel line target. Normally
the line-width and space-width are
equal.
An eye which has been exposed to
light stimuli of relatively high
intensity and therefore has become
relatively insensitive to lower
intensities.
Note: For judging or naming color
light-adapted eyes are necessary
because color perception is absent
in the dark-adapted eye.
Note: In the Figure below, A and B
form a line pair.
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LIVID COLOR [5]
A leaden tint (blue, violet, or
green) approaching black.
LOCI OF CONSTANT HUE [18]
Curves on the CHROMATICITY DIAGRAM
representing colors that have same
hue under prescribed conditions.
LOCI OF CONSTANT SATURATION [18]
Curves on the CHROMATICITY DIAGRAM
representing colors that have same
saturation under prescribed condi-
tions.
LOGARITHM (LOG) [4]
The exponent that indicates the
power to which a fixed number must
be raised to obtain a given number.
and yellow). The glasses within
each set vary in optical density
and are designated numerically
(1R, 2R, 1B, 2B, lY, 2Y, etc.)
so that the numbers are additive
(1B+2B = 3B, etc.) and any com-
bination with equal numerical
values of all three colors yields
a neutral (achromatic) color. By
combining these glasses properly
most colors can be matched. For
example, a red color might be
matched by combining glasses 1R
and 2Y. This red would be
designated as 1R + 2Y. These
Lovibond glasses are used in a
Lovibond Tintometer (Colorimeter)
in which the glasses are placed
in half the field of view and the
color sample in the other half.
One changes the glasses until a
visual match is obtained.
Logarithms to the base 10 are LOVIBOND COLORIMETER
frequently used; for example, the
log of 1,000 is 3 since 103 = 1,000. See LOVIBOND COLOR SYSTEM
LONGITUDINAL CHROMATIC ABERRATION [4] LOVIBOND NUMBERS
An aberration which affects the
sharpness of all parts of an image
because different colors come to a
focus at different distances from
the lens.
Numbers proportional to the
densities of three glass colorants
(a yellow, a red, and a blue)
required to modify a standard
light source to produce a
color match.
A system based on the use of 3 sets
of transparent glasses, red, blue,
and yellow (actually magenta, cyan,
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LOVIBOND TINTOMETER
See LOVIBOND COLOR SYSTEM
LUMEN
The LUMINOUS FLUX per unit SOLID
ANGLE from a point source whose
intensity is one CANDELA.
LUMINANCE
The luminous intensity of any
surface in a given direction per
unit of projected area of the
surface as viewed from that
direction.
Note: The unit is the candela per
square meter. See Figure 4.
The ratio of the LUMINANCE of a
body to that of a perfect reflect-
ing diffuser identically illu-
minated.
LUMINANCE PURITY
See COLORIMETRIC PURITY
LUMINESCENCE [8]
Visible glow of certain substances
when subjected to stimulation by
electromagnetic radiation,
electric fields, or heat. The
general term luminescence also
embraces phenomena such as electro-
luminescence, fluorescence, and
phosphorescence.
A measure of the visibility or
brightness-producing capacity of
light consisting of the ratio of
photometric quantity to correspond-
ing radiometric quantity.
The coefficients by which the
COLOR-MIXTURE DATA for any color
need be multiplied so that the
sum of the three products is the
LUMINANCE of the color.
Note: For a single set of
primaries and a single observer
these coefficients are the same
for all sample colors and may be
interpreted as the luminosities
of the primaries. For the
CIE 1931 2? STANDARD OBSERVER
and primaries, these coefficients
are 0, 1, 0, all luminosity being
associated with the tristimulus
value Y.
LUMINOSITY CURVE (PHOTOPIC CURVE,
VISIBILITY CURVE, LUMINOSITY
FUNCTION)
Curve of the relative LUMINOSITY
of the visual spectrum plotted
as a function of wavelength.
Note: In the figure below, the
photopic luminosity curve of the
human eye is presented.
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1.1
1.0
0.9
o 0.8
0.7
0.6
D.5
0)
> 0.4
0.3
e -I 0.2
Wavelength, nm
LUMINOSITY FACTOR (K)
The Luminosity Factor for radiation
of a particular wavelength is the
ratio of the LUMINOUS FLUX at that
wavelength to the corresponding
RADIANT FLUX. It is expressed in
lumens per watt.
Note: K = Fx/4
where: F = LUMINOUS FLUX
~ = RADIANT FLUX
X = WAVELENGTH
LUMINOUS [5]
Characteristic of the illuminant
mode of appearance; glowing, having
the appearance of emitting light.
LUMINOUS DENSITY [5]
Luminous energy contained in a
unit volume of space.
The LUMINOUS REFLECTANCE that a
perfectly diffusing surface would
have to possess in order to appear
as bright as the object in question
under the same illuminating and
viewing conditions.
The ratio of the LUMINANCE of the
second surface of a light-
transmitting specimen to the
illuminance of the first surface.
LUMINOUS EFFICIENCY [5]
The Luminous Efficiency of RADIANT
ENERGY is the ratio of the LUMINOUS
FLUX to the RADIANT FLUX.
Note: Luminous Efficiency is
usually expressed in lumens per
watt of radiant flux. It should
not be confused with the term
efficiency as applied to a
practical source of light since
the latter is based upon the power
supplied to the source instead of
the radiant flux from the source.
For energy radiated at a single
wavelength, Luminous Efficiency
is synonymous with LUMINOSITY
FACTOR.
LUMINOUS EMITTANCE [5]
The LUMINOUS FLUX being radiated
from a unit area of a primary or
secondary source (lumens per unit
area).
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LUMINOUS ENERGY [5] Note: See Figure 4, and Table 1
in the Appendix.
Evaluation of RADIANT ENERGY
according to its stimulation of
the brightness attribute of visual
perception.
The flow rate of LUMINOUS
ENERGY expressed in LUMENS.
Note: See Figure 4 in the
Appendix.
LUMINOUS INTENSITY [5]
LUMINOUS FLUX emitted per unit
solid angle about a source. The
unit is the CANDELA.
Note: See Figure 4 in the
Appendix.
LUMINOUS REFLECTANCE [5]
Ratio of reflected to incident
LUMINOUS FLUX.
LUMINOUS TRANSMITTANCE [5]
Ratio of transmitted to incident
LUMINOUS FLUX.
LUSTER [5]
The appearance of a surface which
results from its mirror-like
reflection.
A unit of ILLUMINANCE equivalent to
one lumen of incident light per
square meter.
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Elliptical shaped figures on a CIE
CHROMATICITY DIAGRAM joined by the
locus of points that correspond to
colors that are, visually, equally
different from the color at the
center of the ellipse.
by stimulation of the normal
human eye with a wavelength
combination which is the approx-
imate COMPLEMENT of 515 nanometers
(or green).
(2) The COMPLEMENT of GREEN.
MAGENTA DYE
Note: MacAdam Ellipses are equally
different perceptually from the
color (the dot) at the center.
MACULA (MACULA LUTEA; MACULAR AREA;
YELLOW SPOT) [5]
A yellow pigmented area in the
RETINA of irregular shape and
variable from one individual to
another. The FOVEA is found in
the Macula.
A container for rolled film or
photographic plates attached to
the camera body and usually
equipped with automatic mechanisms
that advance and position the
photographic material for exposure.
MAGENTA (MINUS-GREEN)
(1) The purple hue attribute of
vision sensations typically evoked
During the processing of color
films it is the red-blue dye
formed in the green sensitive
layer.
Note: In positive transparencies
it is formed where green wave-
lengths were not imaged, thus
stopping the transmission of green
except where it was imaged. In
negative transparencies it is
formed where green wavelengths
were imaged, thus allowing its
complement (MAGENTA) to be
transmitted.
The bands perceived on either side
of an edge between a light and dark
area due to the brightness differ-
ences. The bands are perceived
parallel to the edge and on the
light side the band is seen as
lighter and on the dark side,
darker.
Note: Mach bands are often diffi-
cult to see and may cause mis-
judgment in choosing the position
of an edge or its midpoint since it
has been shown that people tend to
choose closer to the dark band.
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MAERZ AND PAUL, DICTIONARY OF
COLORS
A dictionary containing 7056
different printed colors mixed
from eight basic colors and seven
gray pigments. The dictionary also
contains 4000 color names for
designating some of the printed
colors.
Essentially a mask is an image
(black and white or single-
colored) of the original to be
copied which, when placed in
both blue and green light, lightens
both the blues and greens. regard-
less of the color of light used to
expose it, a single mask used in
exposing all three color-separation
negatives can accomplish no hue-
shift correction. With two masks,
however, it is possible to correct
not only the relative brightness
and saturation errors but also the
most serious hue-shift errors.
See COLOR MATCH; INVARIANT MATCH;
CONDITIONAL MATCH
registry with the original, affects MAXWELL TRIANGLE
the final copy in some way. In
color reproduction masks are used
to improve color balance and
fidelity by correcting brightness
and saturation errors.
Note: Practically speaking, the
effect of a single mask is to
lighten the reproduction of all
colors complementary to the color
of the filter used in making the
mask. The mask also reduces the
contrast
of the original
and
thereby
permits a higher
printing
contrast
which increases
the
saturation of all colors.
For
example, a magenta filter
absorbs
green light and thus allows less
exposure in the picture than it
does through the other colors.
When the mask has been developed
and registered with the trans-
parency, the greens are effectively
lightened in relation to the other
colors. Similarly, a mask exposed
with a red filter, which absorbs
The equilateral triangle in which
the primaries are represented at
the vertices and other colors that
can be formed by the primaries fall
in specific places in between.
Note: In the figure below is an
example. A color is calculated by
determining the distance it falls
from the sides opposite the apexes.
Thus Color A may be calculated as
2 units of blue, 4 red, and 4 green.
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Intermediate in value or lightness;
between light and dark.
MEMORY COLOR [5]
Color, as remembered, of an object,
film, or illumination. The memory
and other surfaces which possess
the physical feature known as
metallic reflection and which
exhibits chromatic highlights
similar in HUE to the surface
as a whole. Metallic gold, silver,
copper, bronze, chromium, and
aluminum are examples.
colors of an individual exert METAMERIC COLORS
influence in the determination of
the colors of the familiar objects
which he perceives.
Note: Memory of colors is not
reliable. Generally memory colors
emphasize dominant aspects of the
true colors, e.g., reds are redder,
dark-reds are darker and redder,
etc.
MERCURY HYPERSENSITIZING [4]
A method of hypersensitizing
(increasing the sensitivity) con-
sisting of placing a globule of
mercury in the film container.
Colors which have different
SPECTRAL DISTRIBUTIONS but appear
to be identical colors under
certain illuminants or to certain
observers.
Note: According to most experts,
metameric colors should not appear
on color transparencies.
Any two metameric colors.
The mercury vapor will penetrate The phenomenon in which two colors
the film wrappings and exert its are perceived as matching
hypersensitizing effect. Generally in spite of spectral differences.
results in a greatly increased Also, the phenomenon of METAMERIC
log e level. COLORS.
MESOPIC VISION (TWILIGHT VISION) [5] METAMERISM, GEOMETRIC
Vision intermediate between
PHOTOPIC and SCOTOPIC VISION and
consequently attributed to the
combined functioning of the RODS
and CONES.
The phenomenon in which two colors
are perceived as matching when
observed at some sets of illumina-
ting and viewing angles but not
at other sets.
METALLIC COLOR [5] Note: Generally due to differences
between the color materials, e.g.,
Color typically evoked by selective texture, thickness, distribution of
reflection from certain metallic colorants, etc.
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METAMERISM, INSTRUMENTAL
The phenomenon in which two colors
with different spectral curves
have the same color coordinates
when measured on one or more
instruments but different coor-
dinates when measured on other
instruments.
METER-CANDLE
Same as LUX.
METER-CANDLE-SECOND
A unit of exposure in SENSITOMETRY;
one second of exposure at a MICRON
distance of one meter from a light
source of one CANDELA.
METER-LAMBERT (APOSTILB)
A unit of LUMINANCE equal to 1
candela/meter2. 7T
Note: See Table 1 in the Appendix.
METHUIN COLOR ATLAS
A collection of 1,266 printed
colors arranged in orderly
fashion with names for many of
them. Not a highly systematic
collection. In the United States,
the REINHOLD COLOR ATLAS is the
same.
METRIC SYSTEM [4] See also: RAYLEIGH SCATTERING
A system of weights and measures MILLIMETER
(based on the decimal system) which
is the international standard for
scientific use. The meter, the
liter, and the gram are the units
of measures of length, capacity,
and weight, respectively.
MICRODENSITOMETER [4]
A special form of DENSITOMETER for
measuring densities in very small
areas and used for measuring edge
gradients on imagery and granularity
of films.
A unit of length in the metric
system; the thousandth part of a
millimeter or 10,000 Angstrom
units. The standard abbreviation
for micrometer is pm. Formerly
called the MICRON.
MICRO-RECIPROCAL DEGREE [5]
Unit of RECIPROCAL COLOR
TEMPERATURE obtained when one
million is divided by the
temperature in Kelvin. Abbre-
viated mired or prd.
The selective scattering of wave-
lengths of light caused by parti-
cles and molecules in the atmos-
phere having approximately the
same size as the wavelength of the
incident light.
A unit length; 1/1,000 of a meter;
mm is the standard abbreviation for
millimeter.
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MIL
1/1,000 of an inch.
MILLIMICRON
Obsolete term for NANOMETER.
MINUS-BLUE FILTER
A yellow filter which will not
transmit blue wavelengths.
Note: Generally used over an
aerial camera lens to reduce the
transmission of predominant blue
wavelengths caused by ATMOSPHERIC
SCATTERING.
transmission of the blue wave-
lengths and thus reduce the effect
on the imagery.
MIXTURE, LIGHT
Superimposition of two or more
lights.
Characterization of a color
according to whether it is
perceived to belong to an aperture,
a surface, a volume, an illuminant,
etc.
Note: Color transparencies are
said to have "Film Color" as a
MODE OF APPEARANCE.
MINUS COLOR MONOCHROMATIC [4]
A COMPLEMENTARY color. For example, (1) Containing light of one color.
minus-blue is complementary to blue.
(2) A scene composed of nearly
Note: A Minus-color filter is one the same color.
which will not allow that color to
pass through. Thus, a yellow (3) Containing light of a single
filter is a minus-blue filter WAVELENGTH.
because blue is not transmitted.
From above definitions, yellow or MONOCHROMATIC VISION
minus-blue is complementary to blue.
Vision in which no HUES or
MIST SATURATIONS are seen. Only
brightness differences are
Particles of water vapor suspended perceived. The individuals are
in the atmosphere. These particles called Monochromats.
tend to scatter blue light more
than red light. The result is MONOCHROMATOR
called ATMOSPHERIC SCATTERING and
causes a bluish-cast on high- A device that can be used to
altitude imagery. separate or select a single wave-
length from any portion of the
Note: HAZE FILTERS (MINUS-BLUE SPECTRUM of the source.
FILTERS) are used over aerial
camera lenses to reduce the
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Vision resulting when using only
one eye.
MULTILAYER FILM (Continued)
double-coated films for reduction
of HALATION effects and 2- or
3-layer films for color photog-
raphy.
A fringe of color occurring at the MULTISPECTRAL PHOTOGRAPHY
edge of moving images when the
(SPECTRAZONAL)
ADDITIVE COLOR SEPARATIONS are
taken at different instants in
time.
MOTTLED [5]
Unevenly colored; variegated;
mealy, spotted.
MOTTLING [4]
Marks in the form of density
variation which often appear on
negatives or prints caused by
insufficient agitation of the
developer.
MULTIDIRECTIONAL ILLUMINATION [5]
The simultaneous imaging of
several SPECTRAL BANDS; each
band on a separate film or
emulsion layer.
Note: Generally, several (up
to nine have been noted) cameras
are mounted on the same platform,
each with a panchromatic film
and each with a different filter.
Each film will then image a
different range of wavelengths
of the same scene. Color films
are in a sense Multispectral
because each emulsion layer is
sensitive to a different range
of wavelengths.
Multidirectional illumination on MUNSELL BOOK NOTATION
a surface is produced by several
separated light sources of a
relatively small area. It is
characterized by the fact that a
small opaque object placed near
the illuminated surface casts
several shadows.
Munsell color notation as applied
to the hue, value, and chroma
scales of the samples of the
MUNSELL BOOK OF COLOR.
Currently, Munsell Book Notation
is identical with MUNSELL
RENOTATION but this was not
true before 1943.
A film coated with two or more
layers of emulsion of differing
characteristics; these include
Collections (matte and glossy)
with an orderly arrangement of a
series of colored chips. It is
three-dimensional in nature
with the vertical axis
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representing black to white (10
shades) and called VALUE; the
radial axis represents increasing
amounts of color from the center
outward and is called CHROMA; colors
of the different HUES (40 are
represented) surround the vertical
axis. The book contains about
1,000 color samples (both CHROMATIC
MUNSELL COLOR SYSTEM (Continued)
for the samples of the MUNSELL
BOOK OF COLOR. The Munsell Color
System, however, is a notation
system which is and can be used
independent of any set of
samples.
and ACHROMATIC); each adjacent sample MUNSELL HUE
being as perceptually different as
the next adjacent sample. Each
sample color is specified by a
letter-number system of notation
with respect to MUNSELL HUE,
MUNSELL VALUE, AND MUNSELL CHROMA.
MUNSELL CHROMA [5]
(1) Expression of the degree of
departure of an object color from
the ACHROMATIC color of the same
lightness or Munsell Value.
(2) Analogous to Saturation.
Note: The Munsell Chroma scales
have approximately uniform
perceptual steps; under ordinary
observing conditions Munsell
Chroma of a specimen correlates
well with the saturation of the
color perceived to belong to the
specimen.
See also: MUNSELL HUE; MUNSELL
VALUE
The coordinate system comprising
MUNSELL HUE, VALUE, and CHROMA.
It is three-dimensional in nature
and is often arranged as described
HUE in the Munsell Color System.
See HUE.
Color specification in terms of
MUNSELL HUE, MUNSELL VALUE, and
MUNSELL CHROMA, written in the
form of H V/C, e.g., 5R 4/10.
Munsell color notation applied
to HUE, VALUE, and CHROMA scales
in accordance with the recom-
mendations made in 1943 of the OSA
Subcommittee (of the Colorimetry
Committee) on the Spacing of the
Munsell Colors. The original
notations by Munsell were changed
to more nearly reflect
perceptual differences.
MUNSELL VALUE [5]
(1) Expression of the LUMINOUS
REFLECTANCE of an object color
on a scale giving approximately
uniform perceptual steps under
usual conditions of obser-
vation.
(2) Analogous to Lightness
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Note: Munsell Value of an opaque
surface may be found approximately
by taking the cube root of the
LUMINOUS REFLECTANCE according to
the equation V = 25 Y1/3-17 where
V is Munsell Value and Y is
luminous reflectance expressed on
a scale so that Y = 100 for white.
Under usual conditions. of
observation, the Munsell value of a
specimen correlates closely with
the lightness of the color
perceived to belong to the specimen.
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NADIR 14]
PHOTOGRAPHIC NADIR (PHOTO-
GRAMMETRY): the point at which
a vertical line through the
perspective center of the camera
lens strikes the plane, of the
photograph. Also referred to as
the nadir point. GROUND NADIR:
the point on the ground vertically
beneath the perspective center
of the camera lens. MAP NADIR:
the map position for the ground
nadir.
NAGEL ANOMALOSCOPE [18]
Color vision test in which the
observer determines relative
amounts of red and green
necessary to match spectral
yellow.
NANOMETER (nm)
A unit of length in the metric
system; the billionth (10-9) part
of a meter, or thousandth part
of a micrometer, or 10 angstroms.
Formerly called the millimicron.
Customarily used to express the
wavelength of visible light, e.g.,
400-700 nm.
NEUTRAL DENSITY FILTER
See FILTER, NEUTRAL DENSITY.
NEGATIVE
A photographic image on film,
plate, or paper, in which the
ACHROMATIC or CHROMATIC colors
to which the emulsion is
sensitive are reversed or
COMPLEMENTARY, respectively.
NEGATIVE COMPONENT IN COLOR
MIXTURE [18]
Component or primary color that
is mixed with the sample light in
order to change it sufficiently to
obtain a match with a mixture of
the other two components (or
primaries).
NEW LONDON NAVY LANTERN TEST [6]
A test of color vision used to
screen out the more severe
DICHROMATIC defective (red-green
color defects). It uses back-
lighted red, green, and neutral
filters in pairs. The individual
is asked to simply name the colors
of the pairs. The test lights seen
are very small simulating distant
signal lights.
An ACHROMATIC COLOR falling
between black and white; a gray.
A strip of different NEUTRAL
DENSITY FILTERS in discrete steps
or continuous tones.
NM (NANOMETER)
See NANOMETER (nm)
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NODAL POINT [4]
(2) Free of visual defects.
One of two points on the OPTICAL Note: In the Figure below, line A
AXIS of a lens (or a system of is the normal to the surface.
lenses) such that, when all object
distances are measured from one
point and all image distances are
measured from the other.
Note: In the Figure below, the ray
emergent from the second point (N")
is parallel to the ray incident at
the first (N). The first nodal
point (N) is also referred to as NORMAL COLOR VISION
the front nodal point or incident
nodal point and the second point See NORMAL TRICHROMATIC VISION
(N") as the rear nodal point or
emergent nodal point. Also called NORMAL TRICHROMATIC VISION (NORMAL
"node", front node, or rear node. TRICHROMAT)
a Posse meaning normal color
vision. The term trichromatic
means here that the normal observer
needs 3 primary colors (blue,
green, and red) to mix and match
all the colors he can perceive.
NODAL PLANE [4]
The plane perpendicular to the
optical axis at a NODAL POINT.
NONCURLING [4]
A term applied to film which has a
clear gelatin coating on the back
to minimize curl caused by shrink-
age of the emulsion in drying.
NORMAL [5]
(1) In optics, the perpendicular
to a surface at the point where a
ray of light is incident upon a
surface.
NON-SELECTIVE FILTER
See FILTER, NEUTRAL DENSITY
NON-SPECTRAL COLORS
(1) Colors not found in the
SPECTRUM.
(2) Mixtures of 2 or more wave-
lengths of light. Purple is an
example as it represents a mixture
of red and blue light.
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OBJECT COLOR [5]
Color seen as belonging to an
object. This includes surface
and volume colors to the extent
that surfaces and volumes are
perceived as_objects or parts
of objects.
Note: In a strict sense, it is
not legitimate to attribute a
color to an object but only to
the light emanating from it as
perceived by an observer.
The capacity of an object to
modify the color of the light
incident upon it corresponds
to the common concept of the
color of the object. Object
colors are relatively
insensitive to changes in
viewing conditions, viz., they
exhibit the phenomenon of COLOR
CONSTANCY. In addition, objects
tend to be related to particular
colors, e.g., red apples, blue
violets, etc. Thus the
perception of an object's color
may be influenced by previous
experience with the object.
OBJECT-COLOR PERCEPTION [5]
Color perceived as belonging to
a non-self-luminous object.
See Also: OBJECT COLOR
OBLIQUE PHOTOGRAPH [4]
A photograph taken with the
camera axis intentionally
directed between the horizontal
and the vertical. High-oblique
photograph: an oblique
photograph in which the apparent
horizon is included within the
field-of-view; low oblique does
not include the horizon.
The phenomenon in which observers
differ in their judgment as to
whether METAMERIC COLORS do or do
not match. -
Areas located on both sides of
the rear portion of the brain
which are the anatomical-end
of the OPTIC NERVES.
The dominance of the perceptions
of one eye over the other.
Note: When viewing two colors,
one with each eye, one color may
dominate in the field of view
because of OCULAR DOMINANCE.
OLIVE [5]
Any color which manifests a hue
predominantly similar to that of
olive, dark-greenish yellow, a
mixture of yellow, green, and
black. (The complement of
bluish-purple).
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(1) The degree of obstruction to
the transmission of visible light.
(2) Ratio of the measured reflec-
tance of the sample to the reflec-
Note: See Figure 1 in the
Appendix. Generally, people are
not aware of this blind area
because the eyes continually move
and one eye sees the area blind to
the other.
tance measured with the sample over OPTIC NERVE
a white background, the white back-
ground having a reflectance of 89%.
A bundle of elongated axons of the
GANGLION CELLS which passes the
visual information to the
GENICULATE BODY.
Any doctrine to the effect that
color vision can be explained on OPTIC RADIATIONS
the basis of three pairs of
opposing colors such as a red Nerves which carry the visual
whose negative is green, a blue information from the GENICULATE
whose negative is yellow, and BODY to the OCCIPITAL CORTEX.
a white whose negative is black.
See Also: HERING COLOR THEORY;
HURVICH-JAMESON COLOR THEORY
The neural junction where the two
OPTIC NERVES join and then
separate. It is at this point
where all nerve fibers from the
right half of both retinas (left
field of vision) join, leave the
chiasm, and go to the left
GENICULATE BODY while the nerves
of the left half of both retinas
(right field of vision) join and
go to the right GENICULATE BODY.
The term for the two OPTIC NERVES
after they have left the OPTIC
CHIASMA. They differ from the
nerves in that each contains
information from half (left or
right) the field-of-view.
OPTICAL AXIS (PRINCIPAL AXIS) [4]
In a lens element, the straight
line which passes through the
centers of curvature of the lens
surfaces. In an optical system,
the line formed by the coinciding
principal axes of the series of
optical elements.
OPTIC DISC (BLIND SPOT)
OPTICAL CENTER [4]
An area of the Retina where the
optic nerve is formed and leaves
the retina. Contains neither rods
nor cones and thus is a true
blind area of the retina.
The point, usually within a lens,
at which the light rays are assumed
to cross.
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OPTICAL DENSITY (D)
The logarithm of the reciprocal of
the TRANSMITTANCE of a medium.
See Also: ABSORBANCE
OPTICAL SCATTERING
See SCATTERING
OPTICAL WEDGE
A device consisting of a strip
of material--glass, celluloid or
plastic--covered with a pigment
or developed silver emulsion
layer which is clear at one end
and gradually becomes opaque
towards the other. The
transition from transparent to
opaque may take place smoothly
(continuous wedge) or in
regular steps, in which case it
is called a STEP WEDGE.
Note: Generally used as a
comparison device in
determining the DENSITY or
OPACITY of a transparent area.
ORA SERRATA [6]
A thin irregular margin of the
RETINA that represents the
anatomical limit of the
receptor system.
Note: See Figure 1 in the
Appendix.
The hue attribute of visual
sensations typically evoked by
stimulation of the normal retina
with radiation of wavelengths of
approximately 592 nanometers.
ORTHOCHROMATIC [5]
(1) Characterizing the equivalence
between the photographic effect of
various colors upon a photographic
material and the physiological
effect upon the eye.
(2) By old usage, characterizing a
photographic material sensitive to
all colors except red.
ORTHOCHROMATIC EMULSION [5]
A photographic emulsion which is
sensitive to yellow, green, blue,
and shorter wavelengths, but not
to orange or red.
ORTHOPANCHROMATIC [8]
Term used to describe materials
sensitized to all colors of the
visible spectrum that have an
evenly balanced red sensitivity.
In this they differ from the
excessive red sensitivity of
some high-speed panchromatic
emulsions which are produced to
give speed as a first
consideration.
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A color system used to designate
colors by their COLOR CONTENT;
WHITE CONTENT, and BLACK CONTENT.
Also based on the concept that
color content + white content +
black content = 1. There are 24
HUES. Each hue is described by
36 shades (colors) developed by
adding white and black (called
shading or toning) to the HUE.
Each hue and its 36 shades are
described on an OSTWALD COLOR
TRIANGLE. (There are 24 such tri-
angles, one for each hue).
The arrangement of colors of
constant OSTWALD HUE in a triangle
showing the Hue's FULL COLOR
CONTENT, WHITE CONTENT, AND BLACK
CONTENT. There are 24 such
triangles.
Note: The Figure below shows an
Ostwald Color Triangle.
Black
Analygous to saturation
OSTWALD COLORS [5]
A series of several hundred
CHROMATIC and ACHROMATIC samples,
each corresponding to a certain
theoretical pigment combination of
FULL COLOR CONTENT, WHITE CONTENT,
and BLACK CONTENT; designated by a
letter-number system of notation.
Note: The most widely known
collection based approximately
on the OSTWALD COLOR SYSTEM is
the Color Harmony Manual.
See Also: OSTWALD COLOR SYSTEM:
OSTWALD NOTATION
OSTWALD HUE [5]
Designation of DOMINANT
WAVELENGTH or HUE by arbitrary
numbers ranging from 1 to 24.
Colors are designated by numbers
and letters. The 24 Hues are
numbered from 1 to 24. Each of
the 36 shades are designated by
2 letters, each letter
designating WHITE CONTENT and
BLACK CONTENT of the shades.
The theoretical color which
contains neither black nor white.
Mixtures of a SEMICHROME with
black.
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Mixtures of a SEMICHROME with
white.
OVERCAST SKY
See SKY, OVERCAST
OVERDEVELOPMENT [4]
Result of leaving film or paper
in the DEVELOPER too long,
resulting in excessive density and
contrast. Development continued
beyond the time necessary to
produce normal density and
contrast.
OVEREXPOSURE [4]
Excessive duration of the
interval in which light is
allowed to act on a sensitive
surface in making either a
negative, positive, or a print.
Note: Overexposure results in
excessive density, a shortened
tonal scale, and lack of detail.
In REVERSAL COLOR FILMS it results
in very desaturated, washed-out
colors and detail is lost.
OVERLAP [4]
The amount by which one
photograph covers the same area as
covered by another, customarily
expressed as a percentage. The
overlap between aerial
photographs in the same flight is
called the end lap and the overlap
between photographs in adjacent
parallel flights is called the
side lap.
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PANCHROMATIC PERCEPTION,. COLOR
SENSITIZED MATERIALS with a See COLOR PERCEPTION
response to all colors of the
visible spectrum. PERIMETER
.PARABOLA [4] A device used in PERIMETRY Con-
sisting of a semicircular arm
A parabola is the curve formed by which can rotate about an axis
a point in a plane so that its perpendicular to the visual
distance from a fixed line of the plane. Colored stimuli can be
plane and its distance from a fixed attached at the end of the arm
point of the plane, not on the and moved towards the center.
line, are equal. The importance The observer stares at the center
of a parabola lies in the fact of the arm and is asked to name
that parabolic reflectors will the color when he first perceives
focus a parallel beam of light to it in his peripheral vision.
a point and vice versa.
Note: In the Figure below is a PERIMETRY
parabolic reflector. All reflected
light is focused at a point and The mapping of the COLOR ZONES
vice versa. (the extent colors are perceived
by the RETINA from the FOVEA
outward) of the retina using a
PERIMETER.
The region of the retina remote
from the center of vision.
Generally, the area of the
retina least sensitive to colors.
Vision resulting from light
falling on an area of the RETINA pH [4]
immediately surrounding the FOVEA.
A symbol expressing the degree
Note: Color vision can be of acidity or alkalinity of a
considered Paracentral Vision solution. It is equal to the
since most of the CONES are found logarithm of the reciprocal of
in this zone. the hydrogen ion concentration
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pH [4] (continued)
(LOG10 1/H). A neutral solution
(pure water) has a pH of 7.0 while
alkaline solutions have a higher
pH and acid solutions a lower pH.
For example, photographic
developers are alkaline and have
pH's with 8-11 range.
PHOT [4]
A unit of ILLUMINANCE equal to 1
lumen/square centimeter.
PHOTOELECTRIC COLORIMETER [5]
A photoelectric instrument using
three or four photodetector-
filter combinations to produce
color coordinates easily
transformed into approximate
CIE tristimulus values.
Note: It has not yet been found
possible to build a perfectly
accurate photoelectric
colorimeter, but there are many
useful approximations.
Note: See Table 1 in the Appendix.PHOTOEMISSIVE DETECTOR
PHOTOCONDUCTIVE DETECTOR [5]
A detector of RADIANT ENERGY
depending on change of its elec-
trical resistance when irradiated.
Note: Best known photoconductive
detectors are the cadimium
sulfide or lead sulfide cells
requiring an external source of
potential.
The intensity interval between
that at which light is just sensed
and that at which it is seen as a
color. During this interval light
has neither HUE nor SATURATION.
Detector of RADIANT ENERGY
depending'on the emission of
electrons when irradiated.
Note: Photoemissive Detectors
are commonly known as phototubes
or photomultiplier tubes.
An instrument used in PHOTOMETRY
which measures LUMINANCE (the
intensity of ILLUMINANCE). The
Equality-of-Brightness Photometer
employs simultaneous comparison
of the sample to be measured and
the standard. The Flicker
Photometer presents the sample
and standard to be compared,
successively in the same visual
area.
The light intensity threshold at
which HUE is just perceived.
Usually the first Hues to be
perceived are those corresponding
to wavelengths of 620 nm and
above.
The measurement of LIGHT or the
matching of brightness levels.
Note: Photometry plays an
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PHOTOMETRY (Continued)
important part in SENSITOMETRY .
i.e., the study of the effect of
varying exposure on photographic
emulsion.
PHOTOSENSITIVE [4]
A term used to describe substances
whose chemical compositions are
altered by exposure to light.
Note: The chemicals used in film
emulsions are Photosensitive.
PHOTON [5]
PHOTOPIC VISION (DAYLIGHT VISION)
Vision as it occurs when the eye
is LIGHT-ADAPTED and can fully
discriminate all colors.
Note: Believed to depend upon
the functioning of the retinal
CONES instead of the RODS alone.
See Also: LUMINOSITY CURVE
PHOTORECEPTORS (RODS; CONES)
A general term referring to both
the RODS and CONES.
PHOTOVOLTAIC DETECTOR
(1) In quantum theory, the photon Detector of RADIANT ENERGY
is the smallest unit of radiant generating a potential or voltage
energy. when irradiated.
(2) An obsolete unit of visual Note: The most common
stimulation defined as that Photovoltaic Detector is the
illumination upon the retina which selenium or barrier layer cell.
results when a surface brightness
of 1 candela per square meter is PHYSICAL DEVELOPMENT
seen through a pupil of 1 square
millimeter area. The development of the latent
image by deposition upon it of
Note: The term TROLAND is now used silver contained in the
instead of Photon when referring developing solution itself
to units of visual stimulation. instead of making use, as in
See ADAPTATION, LIGHT; LIGHT-
ADAPTED EYE
the more usual chemical
development, of the silver
already present in the emulsion.
The name attached to a COLORANT
when it is used in a binder such
as paint.
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The outer layer of the RETINA PLANCKIAN LOCUS
where the light sensitive ends of
the RODS and CONES lie. Locus of points on a
PINK
CHROMATICITY DIAGRAM
representing the CHROMATICITIES
of blackbodies at various
A very light red, reddish-orange, temperatures.
or reddish-purple.
PITCH [4]
Note: See Figure 2 in the
Appendix.
(1) Air Navigation: A rotation of PLANCKIAN RADIATOR
an aircraft about the horizontal
axis normal to its longitudinal Any radiator having the
axis so as to cause a nose-up or CHROMATICITY and SPECIAL POWER
nose-down attitude. DISTRIBUTION of a BLACKBODY.
(2) Photogrammetry: A rotation of POINT SOURCE OF LIGHT
the camera or platform about
either the Y photograph axis or
the exterior Y axis; tip or
longitudinal tilt. In some
photogrammetric instruments and
in analytical applications, the
symbol phi (~) may be used.
Note: Pitch causes smearing or
streaking in direction of flight
to occur on the image.
PLANCK'S LAW [5]
The spectral emittance (WX)
of a blackbody can be expressed
as follows:
WX = 211c 2 hX-5 (ehc/akT-l)-1
where c = speed of light
h = Planck's constant
X = wavelength
T = absolute temperature
A theoretical source of light
whose size may be defined as
being that of a "point".
Note: A point source of light
is a practical impossibility,
but the mathematical processes of
optics are greatly simplified by
making calculations for light
rays proceeding from a
mathematical point.
The act or process of filtering
light in such a way that the
vibrations are restricted to a
single plane.
Note: According to the wave
theory, unpolarized light
vibrates in all planes
perpendicular to the direction
of propagation. On passing
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POLARIZATION (Continued)
through or contacting a
polarizing medium (such as
Polaroid or a Kerr cell), ordinary
light becomes plane-polarized;
that is, its vibrations are
limited to a single plane.
A filter which passes light waves
vibrating in one direction only.
Used over the camera lens to cut
down or remove polarized rays
where they may constitute
objectionable reflections from
glass, water, or other highly
reflecting surfaces.
A system of SURFACE COLORS based
on the mixture of known
proportions of PIGMENTS.
red; or violet, green, and red)
from which most other colors may
be produced by ADDITIVE SYNTHESIS.
(2) The colors (cyan, magenta
and yellow) from which most
other colors may be produced by
the SUBTRACTIVE COLOR PROCESS.
Note: There is nothing absolute
about primary colors. The above
have been selected because more
colors can be reproduced by
mixing these colors than
any other three colors.
See Also: PSYCHOLOGICAL
PRIMARIES
A body or object emitting light
by virtue of a transformation
of energy into RADIANT ENERGY
within itself.
A photograph having approximately PRIMARY LUMINOUS STANDARD [51
the same rendition of tones or
colors as the original subject, A light source by which the unit
i.e., light for light and dark for of light is established and
dark. from which the values of other
standards are derived.
Note: A positive may be copied
from an original negative or
processed directly using the
REVERSAL PROCESS and REVERSAL
FILMS.
PRIMARY COLOR(S) (PRIMARY HUES;
PRIMARIES)
PRINCIPAL AXIS
See OPTICAL AXIS
PRINCIPAL FOCAL POINT
See FOCAL POINT
(1) The colors (blue, green, and
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PRINCIPAL HUES respect to each other.
In the terminology used in the Note: Prisms are sometimes used
Munsell Color System, the to disperse light into bands of
Principal Hues are the five hues colors. These colors are called
from which the complete hue PRISMATIC COLORS.
circuit is derived. They are red,
yellow, green, blue, and purple. PRISMATIC COLORS
PRINCIPAL PLANES [5] A term applied to the seven
simple colors (violet, indigo,
The planes perpendicular to the blue, green, yellow, orange, and
optical axis in which lie the red) which result from passing
nodal points of a lens. a ray of white light through a
prism.
See Also: NODAL POINTS; NODAL
PLANE PRISMATIC SPECTRUM
PRINCIPAL POINTS [5] The spectrum of colors formed by
a PRISM.
For lenses used in air, the same
as the NODAL POINTS. See Also: PRISMATIC COLORS
The densities measured to indicate The chemical treatment of exposed
the effect a negative or film to form a permanent visible
transparency will have when used image from the LATENT IMAGE.
with a particular printer and
print material. These PROTANOMALOUS VISION (PROTANOMALY;
measurements must be A PROTAN)
representative of the response of
the material and exposing source. A form of the defective color
vision called ANOMALOUS
Note: For color printing the TRICHROMATISM.in which more red
Printing Density of each dye is required in a mixture of red
layer should be determined for and green to match a yellow than
proper exposure of all layers. in the case of the normal
trichromat. The relative visual
PRISM sensitivity is less than normal
in the red, orange, and yellow
An optical solid made of glass, regions of the spectrum. Hue
quartz, or other transparent discrimination is poor in the red
material with at least two polished to green region of the spectrum.
plane surfaces, inclined with
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PROTANOMALOUS VISION (PROTANOMALY;
A PROTAN)
(Continued)
Note:
In the
population
an
estimated 1.0%
of males
and .02%
of females are
affected
[6].
PROTANOPIA (A PROTANOPE)
A form of the defective color
vision called DICHROMATISM in
which the relative spectral visual
sensitivity is much less than the
normal in the red, orange, and
yellow regions of the spectrum
and in which colors can be
matched by a mixture of yellow and
blue stimuli. The eye is less
sensitive than normal or "blind"
to reds; therefore, reds and their
Note: There are a number of
color vision tests which use these
plates including the American
Optical Company Hardy-Rand-
Rittler Pseudo-Isochromatic
Plates, Ishihara, Dvorine,
Bostrom, and Rabkin.
The four psychologically simple
or unique hues of NORMAL color
perception (blue, green, yellow,
and red). The HUES are perceived
as being unique in the visual
spectrum: thus the red is neither
bluish nor yellowish nor greenish;
the yellow is neither reddish
nor greenish nor bluish; etc.
COMPLEMENTS, blue-greens, are seen PUPIL
as gray. A Protanope's colors can
be matched with mixtures of yellow
and blue.
Note: In the population an
estimated 1.0% of males and .02%
of females are affected [6].
The aperture through which light
is admitted to the retina. It
changes in diameter (2 to 8
millimeters) with variations in
luminance.
Note: See Figure 1 in the
PSEUDOSCOPIC IMAGE appendix.
An image in which the normal
impression of stereo relief is
reversed.
PUPIL, ENTRANCE
PSEUDO-ISOCHROMATIC CHARTS OR PLATES PUPIL, EXIT
Charts for testing color See EXIT PUPIL
deficiency comprised of colored,
spots or dots which yield a PUPILLA
recognizable pattern (number,
letter, irregular line) to a See OPTIC DISC
normal observer but yield a
different or non-recognizable
pattern to an abnormal observer.
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See COLORIMETRIC PURITY;
EXCITATION PURITY
(1) The JUST NOTICEABLE
DIFFERENCE in PURITY.
Note: In the Figure below is
shown the JNDs in purity of
wavelengths (a) 440 nm,
(b) 490 nm, (c) 540 nm, and
(d) 640 nm.
16
14
12
n
5 10
8
6
4
2
100 80 60 40 20 0
Percent purity
(2) The JUST NOTICEABLE DIFFERENCE
between white and a spectral color.
Note: In the Figure below is
shown the JND steps from white
for the spectrum in Nanometers.
_y=
~~,
PURE COLOR [5]
Any color which, like the SPECTRUM
COLORS, approaches the condition
required for maximum saturation;
free of added mixtures of black
and white.
PURKINJE AFTER-IMAGE
See AFTER-IMAGE, PURKINJE
PURKINJE PHENOMENON (PURKINJE
SHIFT)
As brightness is decreased, the
blue and green wavelengths do
not darken as fast as red and
orange wavelengths. The
phenomenon is related to the
shift in retinal sensitivity
during the transition from
PHOTOPIC (cone) to SCOTOPIC
(rod) VISION.
(1) A series of distinctive
reddish-blue hues which are
caused by combinations or
mixtures of long (red) and
short (blue) wavelengths of
light and are not produced by
any single wavelength.
(2) The COMPLEMENT of yellow-
green (~560 nm).
(3) In the CIE COLOR SYSTEM,
Purples lie in the region bounded
by the straight line connecting
the blue end of the spectrum with
the red end and the straight lines
from the achromatic point to the
red and blue ends of the spectrum.
See Figure 2 in the Appendix.
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In the CIE CHROMATICITY DIAGRAM it
is the straight line connecting
the ends of the SPECTRUM LOCUS.
Note: See Figure 2 in the
Appendix.
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Q-FACTOR
See CALLIER QUOTIENTS
QUART
In liquid measure, equal to 2 pints
or 32 fluid ounces. Metric
equivalent 0.946 liters.
A camera lens made of quartz
rather than glass. Transmits
ultraviolet rays for special
photography.
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A test for defective color vision
which, in part, uses PSEUDO-ISO-
CHROMATIC PLATES.
The amount of RADIANT FLUX per
unit SOLID ANGLE and unit
projected area of surface of the
light source.
The RADIANT POWER emitted per
unit SOLID ANGLE in a specified
direction.
Note: The unit is The Watt/
Steradian.
RADIANT POWER
See RADIANT FLUX
RADIANT REFLECTANCE [5]
The ratio of the RADIANCE of the
body to that of a perfect
reflecting diffuser identically
irradiated.
RADIANT ENERGY [5]
Energy traveling through space in
the form of ELECTROMAGNETIC WAVES
of various lengths.
Note: Usually measured in units
of energy such as ergs, joules,
calories, or kilowatt hours.
The flow rate of radiant energy.
It is expressed preferably in
watts or in ergs per second.
Ratio of reflected to incident
RADIANT FLUX
RADIANT TRANSMITTANCE [5]
Ratio of transmitted to incident
RADIANT FLUX
RADIATION [20]
Emission on transfer of energy in
the form of ELECTROMAGNETIC WAVES.
An emitter of radiant energy.
RADIATOR, COMPLETE; RADIATOR, FULL;
RADIATOR, IDEAL
All synonyms for BLACKBODY.
RADIANT FLUX DENSITY [20]
The ratio of RADIANT FLUX at an
element of surface to the area
of that element.
RADIANT INTENSITY [20]
RATIOMETER [5]
Any device used to test the
ACTINIC equality of differently
colored lights transmitted to
the photographic material in
making COLOR SEPARATION
NEGATIVES.
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D AL
RAY, EMERGENT
A ray of light leaving a medium.
RAY, INCIDENT
A ray of light falling on or
striking a surface.
RAY OF LIGHT [12]
The geometrical concept of a
single element of light
propagating in a straight line
and of infinitesimal cross
section; used in analytically
tracing the path of light through
an optical system.
A trigonometric calculation of the
path of a light ray through an
optical system.
RAYS, MARGINAL
imagery the Rayleigh Scattering
by the atmosphere causes imagery
to have a bluish overcast. In
addition, moist, humid air will
scatter more than dry, arid air.
Thus imagery collected over
deserts suffers less from
Rayleigh Scattering.
A rgciprocal of COLOR TEMPERATURE
(10 /T) usually expressed in
MICRORECIPROCAL DEGREE
(abbreviated mired, or bird).
Note: Reciprocal color
temperature provides a more
uniform chromaticity scale than
does color temperature itself:
a given small interval in
Reciprocal Color Temperature is
approximately equally perceptible
as a difference in CHROMATICITY,
regardless of color temperature.
For example a difference of 100
K at 20,000 K is about as
The rays of light passing through perceptible as a difference in
an optical system near the edge of chromaticity as 10 K at 2000 K.
the APERTURE.
RECIPROCITY FAILURE (RECIPROCITY
RAYLEIGH SCATTERING EFFECT) [4]
The scattering of light by Photographic materials do not
particles or molecules whose size , attain the same density from an
is smaller than the wavelength of exposure by a high-intensity
the ray of light being scattered. light source acting for a short
The intensity of the scattered
light is inversly proportional to
the 4th power of the wavelength.
Thus, short wavelengths (blue) are
scattered to a greater extent than
long wavelengths (red).
Note: On high-altitude color
time as from an exposure by a
low-intensity light source acting
for a longer time, even though
the product of time and intensity
is the same in both cases. For
example, when the intensity of
the light is doubled, halving the
exposure time does not result in
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RECIPROCITY FAILURE (RECIPROCITY
EFFECT) [4] (Continued)
exactly the same DENSITY. This is
called Reciprocity Failure. It is
present to some degree in all
photographic materials.
RECIPROCITY LAW (BUNSEN-ROSCOE LAW)
The density obtained on an
emulsion is primarily a function
of EXPOSURE independent of the
actual light intensity or time
considered separately.
Note: This law does not hold
strictly for any emulsion and
some deviate considerably from
the law. This deviation is
called RECIPROCITY FAILURE.
An instrument used to provide a
graph of the SPECTRAL REFLECTANCE
of opaque samples or the SPECTRAL
TRANSMITTANCE of transparent
samples, as a function of the
wavelength.
RECURRENT VISION [5]
A succession of POSITIVE and
NEGATIVE AFTERIMAGES or after-
sensations.
See Also: AFTER-IMAGE
RED
(1) The hue attribute of visual
sensations typically evoked by
stimulation of the normal human
eye with radiation of wavelengths
approximately 630 nm.
(2) Any hue predominantly
similar to that of the typical
red.
(3) The COMPLEMENT of Blue-
green (521 nm).
RED BLINDNESS
See Protanopia
RED-GREEN BLINDNESS
A common form of partial
color-blindness or DICHROMATISM
in which red and green stimuli
are confused because they are
seen as various saturations and
brightnesses of yellow, blue, or
gray.
See Also: PROTANOPIA:
DEUTERANOPIA
RED-SIGHTED
See ERYTHROPSIA
REFLECTANCE
The ratio of the reflected RADIANT
or LUMINOUS FLUX to the INCIDENT
FLUX.
Color seen as reflected from a
perceived object.
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REFLECTED LIGHT Reflectivity at a specified
wavelength.
Rays of INCIDENT light turned back
or "rebounded" from a surface. REFLECTOR
REFLECTION A reflector is a device which is
used to redirect light by
Light rays being returned from a reflection in a desired direction
surface. or directions.
REFLECTION, ANGLE OF [4] REFRACTING PRISM [4]
The angle at which a reflected ray A prism that deviates a beam of
of light leaves a surface as light by REFRACTION. The
measured from the NORMAL. angular deviation is a function
Note: Angle 0 is angle of
reflection.
of the wavelength of light;
therefore, if the beam is
composed of white light, the
PRISM will spread the beam into
1 '101 a spectrum of colors.
L
Defined as: D = 1og10( 1
)
Where R is the REFLECTANCE of the
sample being measured.
REFRACTION [12]
The bending of a light ray or the
change in its direction in
passing from one transparent
medium into another which has a
different REFRACTIVE INDEX, e.g.
air into glass.
Note: Refraction occurs because
the velocity of light varies
The total REFLECTANCE of a layer according to the density of the
of material of such a thickness media.
that there is no change of
reflectance with further increase REFRACTION ANGLE [4]
in thickness.
The angle between the refracted
Note: See Figure 4 in the ray and the normal when a ray of
appendix. light passes through a
transparent substance. The
REFLECTIVITY, SPECTRAL [5] refracted ray is bent at an
angle from the line of the
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REFRACTION ANGLE [41 (Continued)
incident ray.
Note: A is the refracted ray and
B is the incident ray. Angle 8
is the Refraction Angle.
B
.1 B
(1) The ratio of the velocity of
light in a vacuum to the velocity
of light of a particular
wavelength in any substance is
called the refractive index of
the substance for light of that
particular wavelength.
(2) A measure of the power of a
substance to refract (to bend a
ray of light or change its
direction) light. It is the
ratio:
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Note:
The
greater the directional
change
the
higher the Refractive
Index,
e.g.
for air the index is
1.00029
and
for glass, from 1.5
to 1.8.
A device, usually of prismatic
glass, which redirects light
in desired directions by
REFRACTION.
REGISTER [5]
To cause to correspond exactly;
to adjust two or more images to
correspond with each other.
Such correspondence may be
required either in printing or
in projection.
Regular transmission is that in
which the transmitted light is
not diffused.
U.S. name for the METHUIN COLOR
ATLAS.
RELATIVE APERTURE [4]
For a photographic lens, the
ratio of the EQUIVALENT FOCAL
LENGTH to the diameter of the
ENTRANCE PUPIL. Expressed as
f/4.5 or f:4.5; also called
f-NUMBER.
RELATIVE TILT [12]
when ray is incident from the air
side of a glass air boundary. The tilt of a photograph with.
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RELATIVE TILT [12] (Continued)
reference to an arbitrary plane,
not necessarily a horizontal
plane, such as that of the
preceding or subsequent photograph
in a strip.
.RESOLUTION [4]
(1) The minimum distance between
two adjacent features, or the
minimum size of a feature, which
can be detected by a photographic
system. For photography, this
distance is usually expressed in
LINE PAIRS per millimeter
recorded on a particular film,
under specified conditions. If
expressed in size of objects or
distances on the ground, the
distance is termed Ground
Resolution.
(2) A measure of RESOLVING POWER
Note: Color imagery may appear to
have better resolution that what
it, in fact, has due to the
visibility of small color
differences.
(1) Expression of the fineness of
detail that can be recorded by a
lens/emulsion or collection
system. Usually it is stated as
the maximum number of lines per
millimeter that can be resolved
(i.e., seen as separate lines) in
the image. The resolving power of
a lens, film, or their combination
varies with the contrast of
the TEST CHART and normally
varies also with the orientation
and position of the chart within
the field of view.
(2) The minimum size of an
image that can be resolved by the
eye. It's roughly 25 to 50
seconds of arc.
RESOLVING POWER, CHROMATIC [15]
Some optical components such as
prisms and gratings are used,
not to resolve two or more
object points but rather to
separate two wavelengths of
nearly equal value. The ability
of an optical instrument to
separate two wavelengths is
called Chromatic Resolving Power
and is specified as the ratio of
the shorter wavelength divided
by the difference between the
wavelengths.
A network of minute depressions
or corrugations in-a negative,
produced -- either accidentally
or intentionally - by any
treatment resulting in rapid
expansion and shrinkage of the
swollen gelatin. Reticulation
may be produced by solutions
which are too warm or too
alkaline or by forced drying in
an air current which is too hot.
Note: The gelatin appears
similar to cracked, dried mud.
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The innermost layer of the three
major layers of the eyeball, upon
which the visual image is focused
and serves as receptor organ for
vision. In the human Retina 10
layers are distinguished, and
the RODS and CONES are within the
second layer from the exterior.
Note: See Figure 1 in the
Appendix.
RETINAL FIELD [5]
The extended mosaic of the ROD
and CONE receptor elements of the
retina which.forms something of
an anatomical correlate of the
visual field.
RETINAL ILLUMINANCE [5]
The illuminance on the retina,
the usual units being the TROLAND
and the LUX.
as leaving their picture plane
or physical plane and withdrawing
further from the observer.
Note: This illusion may cause
exaggerated depths when viewing
Retreating Colors through a
stereoscope.
REVERSAL FILMS, COLOR
(1) Color of the processed film
is same as the original scene or
is POSITIVE.
(2) Color films in which the
residual silver halide is used
to produce the positive dye image.
Method of developing film first
as a negative silver image, and
then reversing the color values
to form a positive.
RETINAL IMAGE [5] RIDGWAY COLOR SYSTEM
(1) The pattern of RADIANT ENERGY
on the retina corresponding to
external objects.
(2) The image lying on the retina
that is being viewed.
An early system of 1115 pigment
colors chosen to represent by
relatively equal steps a wide
range of variation in HUE,
SATURATION, and LIGHTNESS.
RMS (ROOT MEAN SQUARE) GRANULARITY
RETINAL RIVALRY
See BINOCULAR RIVALRY
RETREATING COLORS
These are generally blues and
greens which tend to be perceived
Approximately the standard
deviation in DENSITY produced by
the granular structure of an
emulsion when uniformly exposed
and developed as measured by a
DENSITOMETER.
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A rod-shaped structure found in
the RETINA of the eye which
constitutes a specific receptor
for SCOTOPIC VISION.
Note: The rods in the human eye
are 0.04 to 0.06 mm long and
about 0.002 mm in diameter.
Distinguish from retinal CONES,
another visual receptor; the Rods
contain the chemical Visual Purple
and are believed to operate for
achromatic (gray) visual qualities
at low light levels, while the
cones for chromatic and achromatic
at higher light levels; the rods
and cones form the second layer of
the retina from the outside lying
just within the layer of pigmented
cells; it is estimated that there
are 130,000 rods in the human
retina; at the FOVEA CENTRALIS
there are no rods, farther out
they are more numerous than the
cones.
Sight or vision in which only RODS
function; the CONES of the retina
do not participate. Also called
TWILIGHT VISION, SCOTOPIC VISION.
ROLL [41
(1) Air navigation. A rotation of
an aircraft about its longitudinal
axis so as to cause a wing-up or
wing-down attitude.
(2) Photogrammetry. A rotation
of a camera or a photograph-
coordinate system about either the
photograph x axis or the exterior
X axis. In some photogrammetric
instruments and in analytical
applications, the symbol omega
(w) may be used.
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SAFELIGHT [4]
A lamp for use in the darkroom
which supplies light of a color
which will not affect the
photographic material within a
reasonable time. Different
photographic materials require
different safelight filters.
Note: Rarely recommended for
fast color or panchromatic films.
SATURATION
analogous to SATURATION .
SCALE [4]
(1) The full range of tones
(grays or colors) which a
photographic paper is capable of
reproducing is called the "scale"
of the paper.
(2) The ratio of a distance on
a photograph or map to its
corresponding distance on the
ground. The scale of a
photograph varies from point to
(1) The degree to which any point because of displacements
CHROMATIC COLOR (possessing a caused by tilt and relief, but it
HUE) differs from an ACHROMATIC is usually taken as f/H where
COLOR (gray) of the same lightness. f is the principal distance of
(2) The amount of "color" in a
color sample. The more "red" in
a red color the higher its
saturation.
(3) The state of being
saturated. A "saturated" red is
a very vivid red.
SATURATION SCALE [5]
the camera and H is the height
of the camera above mean
ground elevation. Scale may be
expressed as a ratio, 1:24,000;
a representative fraction,
1/24,000; or an equivalence, 1
in. = 2,000 ft.
The phenomenon of light diffusing
or dividing in part into a variety
A graduated series of colors which,! of different directions in passing
under appropriately controlled through a medium.
conditions of observation, are
perceived to vary by uniform See RAYLEIGH SCATTERING; MIE
steps in SATURATION alone. SCATTERING
See PURITY DIFFERENCES The outer protective layer of the
eyeball.
SATTIGUNG [5]
Note: See Figure 1 in the
In the DIN COLOR SYSTEM; Appendix.
123
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SCOTOPIC ADAPTATION
See ADAPTATION, DARK
SCOTOPIC VISION [5]
Vision experienced by the normal
eye when adapted to very low
levels of illumination. The
maximum of the relative spectral
visual sensitivity is shifted to
510 nm and the spectrum is seen
uncolored. The ROD receptors in
the retina are considered to be
the active elements under these
conditions.
standard calibrated by comparison
with a PRIMARY STANDARD. The
use of the term may also be
extended to include standards
which have not been directly
measured against the primary
standards but derive their
assigned values indirectly from
the primary source.
SELECTED ORDINATE METHOD OF
COLORIMETRIC CALCULATION [5]
A method of INDIRECT COLORIMETRY
in which the usual numerous
multiplications are avoided by
summation of the SPECTRAL
DISTRIBUTION data at specially
selected, nonuniformly spaced
wavelengths.
A chemical surface layer which SELECTIVE ABSORBER
forms on developers, particularly
pyro. Should be removed to A medium which does not absorb
prevent marking of negatives.
A line or axis formed by the
central ray of an oblique bundle
of rays passing through a lens.
SECONDARY LIGHT SOURCE [5]
A body or object transmitting or
reflecting light falling on it
from any other PRIMARY or
SECONDARY LIGHT SOURCE.
Note: The surface of a light-
table is a Secondary Light Source.
,SECONDARY STANDARD [5]
A secondary standard is a
wavelengths of light equally.
See ABSORPTION, SELECTIVE
SELECTIVE RADIATOR [5]
RADIATOR having SPECTRAL
EMISSIVITY that is different for
different wavelengths of the
spectrum.
Note: A colored light is a
Selective Radiator.
SELECTIVE SCATTERING [5]
Scattering of RADIANT ENERGY so
that the ratio of scattered flux
to incident flux varies with
wavelength.
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SELECTIVE SCATTERING [5] (Continued) the response of a light
sensitive material to a range of
See Also: RAYLEIGH SCATTERING, exposures. There are two types
of sensitometers: one which
subjects the sample of material
SEMICHROME to a series of lengthening
exposures under a light of
See OSTWALD SEMICHROME constant intensity, and the
other which exposes adjacent
SENSATION, COLOR [5] strips of the material for the
same length of time to a
Primitive awareness or uninter- range of light intensities.
preted conscious response to
stimulation of a visual receptor. SENSITOMETRIC CURVE
Note: It is very difficult and
generally unnecessary to
distinguish Color Sensation from
COLOR PERCEPTION (which is a
better term for the awareness of
color in the visual field).
SENSITIZED MATERIAL [8]
A strip of film exposed
(generally through a STEPWEDGE)
and processed under controlled
conditions. Used for quality
control and studying film and
processing characteristics.
films, and papers, etc. - that SENSITOMETRY [8]
have been rendered light sensitive
General term for all types of
photographic material - plates,
either by coating with an
emulsion containing light
sensitive silver salts or by
impregnation with a chemical
sensitizer.
The science of measuring the
sensitivity of photographic
characteristics, e.g., SPEED,
CONTRAST, EXPOSURE LATITUDE, and
FOG, D-MAX, D-MIN, time/rate
(time/gamma) of photographic
materials.
A chemical compound added to the Note: Sensitometry seeks to
emulsion layer to provide establish accurately the
sensitivity to a portion of the relationship between exposure
SPECTRUM. and density for any given
photographic material. The
chief aim of sensitometry is to
derive accurate numerical values
An instrument used in recording for the exposure-density
relationship of a material to
SENSITOMETER [8]
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SENSITOMETRY [8] (Continued)
eliminate guesswork and to state
the results in units which can
be universally applied and
compared.
SHADE [51
A term descriptive of a lightness
difference between colors, the
other attributes of color being
essentially constant. A lighter
shade of a color is one that has
higher lightness but approximately
the same hue and saturation, and
a darker shade is one that has a
lower lightness.
A solution to stop the action of
the DEVELOPER or color developer
and to harden the gelatin.
SHOULDER (of the CHARACTERISTIC
CURVE)
The high density area of the
CHARACTERISTIC CURVE just above its
The unrealistic perception of a
color due to the influence of a
nearby or surrounding color, i.e.,
the juxtaposed colors (CHROMATIC
or ACHROMATIC) are different than
when perceived alone. How
colors affect one another is very
complex but, in general,:
a. A chromatic color tends to
tinge the color near it with
its COMPLEMENTARY COLOR.
b. The eye accentuates the
difference between colors.
c. If two areas are the same
color, the effect of their
juxtaposition is a weakening
of the intensity of their
commonality.
SKY, OVERCAST
The sky when covered by haze or
clouds so that the position of
the sun is obscured and the
illumination on the ground is
even.
STRAIGHT-LINE SECTION. SKYLIGHT
A silver compound sensitive to
light and used in film EMULSIONS
to form a LATENT IMAGE which can
be reduced to visible silver by
DEVELOPMENT or removed and
replaced with colored dyes.
The light received from the sky
as opposed to sunlight.
Note: See Figure 3 in the
Appendix. Note that Skylight is
predominantly blue.
SLOAN COLOR-THRESHOLD TEST [6]
A diagnostic test of color
vision which uses recognition
of colored lights to measure
degrees of red-green deficiencies
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SLOAN COLOR-THRESHOLD TEST [6]
without distinguishing type.
Essentially a colored light is
presented below threshold, then
raised in intensity until the
examinee can recognize the
may confuse amber with red, green
with white, and may be unable to
see red at low intensities.
SLUDGE[4]
A muddy precipitate which forms in
the bottom of processing tanks or
bottles after use.
Note: See Figure below.
N ~
I
&/////J/ i
N2
SNOW-BLINDNESS [5]
A temporary abnormality of color
vision in which all objects are
tinged with red. Caused by
long-continued exposure to very
bright light.
SMALL AREA TRITANOPIA [6]
See SUN ANGLE
Isolated objects of very small
angular size (about 15 minutes or SOLARIZATION [4]
less) produce either a red or
green hue or some shade of gray
(from white to black) when viewed
directly. Green-yellow or
reddish-blue distinctions may not
be perceived.
A law which describes the
behavior of a light ray as it
passes from one media to another.
It is:
N1 sin 61 = N2 sin 62 -
N1 = Index of refraction of
incident medium
6 = Incident angle
N2 = Index of refraction of
refracting medium
62 = Refraction angle
A reversal of the density
gradation sequence in the image
after intense or long-continued
exposure. A still greater
exposure appears to restore the
original sequence of gradation.
Note: The Figure below shows a
CHARACTERISTIC CURVE. As
exposure is increased, the density
on the film eventually will
decrease (dotted line) ; but as
exposure is further increased,
density will begin to increase
again.
N
C
a>
0
Exposure
color. Color-deficient observers
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SOLID ANGLE green, yellow, orange, and red.
The angle measured by the ratio SPECTRAL COMPOSITION
of the surface of the portion of
a sphere enclosed by the conical Distribution of any radiant
surface forming the angle, to the quantity as a function of
square of the radius of the wavelength.
sphere.
Note: In the figure below, 0 is
the Solid Angle.
, sphere
SOURCE (LIGHT SOURCE)
An object emitting radiant power.
Note: In CIE terminology, a
SOURCE is distinguished from an
ILLUMINANT.
See Also: ILLUMINANT
SPECTRAL ABSORBANCE
See ABSORBANCE, SPECTRAL
SPECTRAL BAND
A group of spectrum wavelengths
which can vary from a small
portion to almost the entire
SPECTRUM.
SPECTRAL COLORS [4]
See Also: SPECTRAL DISTRIBUTION
SPECTRAL CROSSTALK
See INTER IMAGE EFFECTS
SPECTRAL DISTRIBUTION
The amounts of a radiant quantity
for the various wavelengths of
the SPECTRUM.
Note: In the Figure below is
shown the Spectral Distribution
of a green leaf. Note that the
radiant quantity (Reflectance) of
each wavelength is shown.
400 500 600
Wavelength nm
SPECTRAL EMITTANCE [20]
An emiLttance based on the radiant
energy per unit wavelength
The continuous band of colors in interval.
the VISIBLE SPECTRUM which are
divided into seven basic spectral SPECTRAL ENERGY DISTRIBUTION
colors: violet, indigo, blue,
The relative energy (amount of
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SPECTRAL ENERGY DISTRIBUTION
(Continued)
light) emitted from a source at
each wavelength.
Note: The plotting of the
distribution (Relative Energy vs.
Wavelength) for a source is
called the Spectral Energy
Distribution Curve.
Ratio of the RADIANT FLUX of a
narrow wavelength range leaving
one face of a body to that
reaching the opposite face.
Note: In Figure below it is the
ratio of A to B.
A
SPECTRAL IRRADIANCE
See IRRADIANCE, SPECTRAL
SPECTRAL POWER DISTRIBUTION
wavelength interval at the
wavelength X.
The RADIANT INTENSITY per unit
wavelength interval.
SPECTRAL REFLECTANCE [20]
The ratio of reflected flux to
the spectrally homogeneous
incident flux.
Note: The measurement of Spectral
Reflectance for each wavelength
is often used to.plot curves
of Reflectance vs. Wavelength for
a particular sample. In the
Figure below is a Spectral
Reflectance curve for a red
sample.
.5
X0 0I i' 1 I L--
400 500 600 700
Wavelength nm
The power (energy per unit of time)
of a light source at each SPECTRAL REGION
wavelength.
A portion of the ELECTROMAGNETIC
Note: The plotting of the SPECTRUM. For example, the
distribution (power vs.wavelength) Visual Spectral Region is from
for a source is called the Spectral approximately 400 to 700
Power Distribution Curve. nanometers.
SPECTRAL RADIANT ENERGY [5] SPECTRAL RESPONSE
The RADIANT ENERGY per unit The response of a light detector
129
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SPECTRAL RESPONSE (Continued)
at each wavelength.
Note: The plotting of the
transparent sample. In the
Figure below is a Spectral
Transmittance curve for a red
filter.
response (generally 0 to 100) vs.
wavelength is called the Spectral
Response Curve.
0
0100
v
SPECTRAL REFLECTANCE of a layer of 50
material so thick that further U)
increase in thickness, however
? 0
~ i I I
great, produces no change in
~ 400 500 600 700
the value of spectral reflectance.
SPECTRAL SENSITIVITY [8]
The response of a photographic
emulsion (or any light-sensitive
material) to each of the separate
colors (or wavelengths) of the
SPECTRUM.
SPECTRAL TRANSMISSION (of a filter)
[5]
The extent to which a filter will
transmit radiant energy of
different wavelengths. Shown
graphically as transmission,
opacity, or density plotted
against wavelength.
Wavelength nm
SPECTRAL VISUAL SENSITIVITY
See Spectral luminosity.
SPECTRAZONAL PHOTOGRAPHY
The imaging of narrow (or wide)
bands of wavelengths by using
appropriate filters over
PANCHROMATIC FILM.
Note: The purpose is to amplify
target /background difference by
using a filter which allows only
the maximum, reflected wavelengths
of the target to be imaged.
SPECTRAL TRANSMITTANCE [5]
See Also: MULTI-SPECTRAL
PHOTOGRAPHY
Ratio of transmitted to incident
RADIANT FLUX of narrow wavelength SPECTROGRAM [4]
range.
A photograph of a spectrum taken
Note: The measurement of Spectral through a filter which permits
Transmittance for each wavelength the study of the absorption and
is often used to plot curves of transmission properties of that
Transmittance vs. wavelength for a filter. A scale on the
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SPECTROGRAM [4] (Continued)
spectrogram shows the relative
amount of transmission of various
colors (or wavelengths).
SPECTROGRAM, WEDGE
See WEDGE SPECTROGRAM
SPECTROGRAPH [5]
A SPECTROSCOPE in which the
ocular lens is replaced by a
photographic plate.
SPECTROMETER [5]
(1) A SPECTROSCOPE fitted with a
divided circle for isolating .or
identifying wavelengths or
regions of the spectrum.
(2) A SPECTROSCOPE fitted with a
divided circle, used to measure
index of refraction of prisms.
The measurement (using a
SPECTROPHOTOMETER) of the absolute
or relative energy within narrow
bands of wavelength frequencies
in the SPECTRUM. Generally
presented in graphs where the
abscissa represents the
wavelengths of the visible
spectrum (-400 to "700
nanometers) and the ordinate
represents the relative energy
or absolute energy (units
depending on type of measurement).
SPECTRUM (VISIBLE SPECTRUM)
The band of colors or visible
wavelengths resulting from white
light being passed through a
PRISM or other refraction mode.
The resulting wavelengths or
spectrum ranges from about 400
to 700 nanometers and the colors
are VIOLET, INDIGO, BLUE, BLUE-
GREEN, GREEN, YELLOW-GREEN
YELLOW, ORANGE, and RED.
An instrument for making a SPECTRUM COLORS
SPECTRUM visible, thereby permit-
ting visual or photographic
(making SPECTROGRAMS) examina-
tions. Usually, consisting of a
slit, a COLLIMATOR, a dispersing
element (usually a PRISM), and a
second lens.
Each wavelength of the SPECTRUM
is a Spectrum Color, but they are
usually grouped and called:
VIOLET, INDIGO, BLUE, BLUE-
GREEN, GREEN, YELLOW-GREEN,-
YELLOW, ORANGE, and RED.
SPECTROPHOTOMETER [5]
A combination MONOCHROMATOR and RADIANT ENERGY of light of one
PHOTOMETER used to measure SPECTRAL frequency or one wavelength.
EMITTANCE, SPECTRAL TRANSMITTANCE,
or SPECTRAL REFLECTANCE.
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SPECTRUM LINE [5]
Any one of the narrow lines, each
representing light of a definite
wavelength, which are observed
on SPECTROGRAMS. Certain groups
of lines being characteristic of
specific chemical elements.
SPECTRUM LOCUS [5]
Note: Such as the reflection
from a mirror.
SPHERICAL ABERRATION [4]
An aberration resulting in light
rays passing through various
zones of a lens coming to focus
at different places along the
OPTICAL AXIS.
The locus of points representing
the colors of the visible SPECTRUM Note: In the Figure below is an
on a CHROMATICITY DIAGRAM is the example, where rays of light
passing at the edge of the lens
Spectrum Locus.
l
Note: See Figure 2 in the
Appendix.
SPECULAR [4]
In SENSITOMETRY applied to a
measurement made by collimated or
essentially parallel light rays;
referring to reflection or
transmission without scattering or
diffusion.
The DENSITY measured by a
densitometer when the incident
light on the sample is highly
COLLIMATED and the collection
angle is small.
SPECULAR REFLECTION [12]
The type of reflection
characteristic of a highly
polished plane surface from which
all rays are reflected at an
angle equal to the angle of
INCIDENCE.
ens
are focused closer to the
than rays passing near its center.
SPHERICAL CANDLEPOWER [5]
The average candlepower of a
lamp in all directions in space.
It is equal to the total LUMINOUS
FLUX of the lamp in lumens
divided by 4 7T.
SPREADING EFFECTS (ASSIMILATION)
The unrealistic perception of a
color because the color of its
surround spreads onto it. A
red object may appear darker if
surrounded by black than if
surrounded by white.
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SPREADING EFFECTS (ASSIMILATION)
(Continued)
See Also: SIMULTANEOUS COLOR
CONTRAST
STANDARD [12]
An exact value (a physical entity
or an abstract concept)
established and defined by
authority, custom, or common
consent to serve as a reference,
model, or rule in measuring
quantities or qualities,
establishing practices or
procedures, or evaluating
results. A fixed quantity of
quality.
STANDARD ILLUMINANT [5]
An agreed upon light source
(real or hypothetical) defined
by its SPECTRAL POWER DISTRIBU-
TION.
The hypothetical observer
possessing the characteristics
of color vision as adopted by
the CIE. These characteristics
of color vision are defined by
the CHROMATICITY CO-ORDINATES
of the equal-energy spectrum
with reference to a specified
set of primary colors.
Note: In the Figure below are
shown the characteristics of the
CIE 1931 2? Standard Observer.
4J
0.32
U 0.28
.'.
w
t41 0.24
a)
U 0.20
. 0.16
O
4' 0.12
0.08
4J
m 0.04
400 500 .600,
Wavelength, nm
0.00
-0.04
-0.08
-0.12
STANDARD OBSERVER, SUPPLEMENTARY
See SUPPLEMENTARY STANDARD
OBSERVER
An object emitting radiant power
with an agreed upon spectral
distribution.
See Also: CIE SOURCES
STEP WEDGE (OPTICAL WEDGE) [4]
A strip of film or a glass plate
whose transparency diminishes
and density increases in
graduated steps from one end to
the other; often used to
determine the density of a
photograph or a COLOR SEPARATION
NEGATIVE.
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STEP WEDGE (OPTICAL WEDGE) [4]
(Continued)
See Also: NEUTRAL DENSITY WEDGE;
OPTICAL WEDGE; WEDGE; STEP TABLET
STEP TABLET (STEP TABLE)
A STEP WEDGE made either photo-
graphically (often called Silver
Step Tablet) or by dispersing
carbon particles in gelatin
(Called Carbon Step Tablet).
two photographs acquired at
different angles.
Note: The stereoscopic vision
of color imagery may be met
with problems not encountered
with black and white.
a. The colors on the image pairs
may be slightly different,
thus resulting in a fused
image of a false color or
BINOCULAR RIVALRY.
b. See ADVANCING COLORS;
RECEDING COLORS
The measure of the SOLID ANGLE
subtended at the center of a c. See CHROMASTEROPSIS
sphere when an area on its surface
is numerically equal to the STILB
square of the radius.
A unit of luminance equal to 1
Note: In the Figure below the candela per square centimeter.
size of the SOLID ANGLE is 1
Steradian.
S/r2 = I = one steradian
Appendix.
The light entering the PUPIL
of the eye near its edge is
less effective in producing
brightness than the light
entering the center of the
pupil. Because of this, the
effective area of the pupil is
smaller than the actual area.
See Also: EFFECTIVE APERTURE
The particular use of binocular
vision to view objects or areas STOP-BATH [11]
to obtain the mental impression of
a three-dimensional view. Usually An acid bath into which films
two different perspectives of an or prints are placed after
object or area are needed, e.g., development to check any further
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STOP-BATH [11] (Continued) SUBSTRACTIVE COLOR PRIMARIES
developing action and to prevent The three primaries are:
stains.
CYAN (BLUE + GREEN),
See Also: HARDENING STOP-BATH MAGENTA (BLUE + RED), and
YELLOW (GREEN + RED).
STRAIGHT LINE (of the CHARACTERISTIC
.CURVE) SUN ANGLE
The linear portion of the
CHARACTERISTIC CURVE.
STRONG COLOR [5]
A color of high SATURATION.
SUBTRACTIVE COLOR PROCESS
(SUBTRACTIVE SYNTHESIS) [11]
A method of creating essentially
all the colors by using cyan,
magenta, and yellow filters to
subtract from white light the
undesired colors. The
subtractive color primaries are
complementary to the additive
primaries (red, green, and blue)
selected so that they absorb only
one-third of the luminous energy
of a white light source. Thus,
white minus CYAN = red; white
minus MAGENTA = green; and white
minus YELLOW = blue. In this way,
by a suitable mixture of the
three subtractive primaries, most
colors can be produced by the
Angle formed by an imaginary
line projected from the sun
passing through the collection
platform and a plane tangent to
the earth and perpendicular to
the normal of the platform.
Note: In the Figure below 0
is the Sun Angle.
subtractive method using only one SUNLIGHT
white light source.
The light emitted from the sun.
Note: Color Positive films use
the Subtractive Color Process by See Figure 3 in the Appendix.
layering CYAN, MAGENTA, and YELLOW
DYES.
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SUNSPOT GLARE [4] LUMINOSITY CURVE. See Figure
below:
A "hot spot", a bright area 2.5r
on an image lacking in detail and
color often present in high-
,... _
-- 2.0
if
are not taken to avoid the
phenomena by using Solar Altitude ;1.5
Nomographs and Sun-Spot Templates.)
SUNRISE AND SUNSET [8]
Light at sunrise and sunset is 0.5
richer in red and orange rays
than in the middle of the day.
Thus, imagery acquired at high
altitude close to sunrise or
sunset may have a reddish or
pinkish overcast.
A tissue body in the brain in
which some OPTIC TRACT fibers
terminate. Here connections are
marls coitl-, rrainial norvoc TTT TV
500 600
WAVELENGTH>, n m
SURFACE-COLOR [5]
Color seen as belonging to a
surface or simply the color
of an illuminated surface.
and Vl serving retiex eye
movements.
SUPPLEMENTARY STANDARD
OBSERVER
Nerve junctions.
SYNCHRONOUS FILM SPEED [4]
A second STANDARD OBSERVER defined Movement of the photographic
in 1961 by the CIE to correspond film in a camera at the same
to the average human perception of rate of speed and in the same
large (10? on the retina or more) direction as the movement of
colored areas, in contrast to the the image during exposure for
small (2?) areas used to define the purpose of eliminating image
the 1931 CIE Standard Observer. motion.
Note: For the SUPPLEMENTARY
STANDARD OBSERVER, the function
y1-0 is not the PHOTOPIC
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Green and red-purple, the colors
that are between the WARM and
COOL colors.
TEMPERATURE, ABSOLUTE
See ABSOLUTE TEMPERATURE
TEMPERATURE, COLOR
See COLOR TEMPERATURE
TEST CHART
Any chart used to test an
acquisition system, e.g., using
a set of LINE PAIRS for testing
resolution or colors for testing
color fidelity and balance.
TEST STRIP [4]
A strip of sensitized paper used
as a preliminary test for exposure
time in contact printing or
enlarging before exposing a full
sheet.
TETARTANOPIA [5]
Form of DICHROMATISM in which
blue and yellow colors are
confused and perceived as neutral.
The existence of this form is
disputed.
A visual quality of the surface
of objects, generally ranging
from smooth to rough and shiny
to dull. These dimensions affect
the perception of colors; two
identical reds may appear
different if one is on a smooth,
shiny surface and the other on a
rough, dull surface. Thus, color
matching should be done with the
colors having the same surface
texture.
Radiation by solids heated to
INCANDESENCE.
Same as BRUNSWIK RATIO except log
luminances are used and thus:
log S - log S'
log L - log S'
See Brunswik Ratio for
explanation.
Note: Thouless Ratio is
preferred over Brunswik Ratio.
THREE-COLOR MIXTURE [5]
It is usually possible to match
a color with a mixture of
suitable amounts of light of
three selected colors.
Note: The colors used for the
mixture are commonly termed
PRIMARIES and are usually red,
green, and blue.
See Also: NEGATIVE COMPONENT IN
COLOR MIXTURE
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THREE-COLOR PROCESS [5]
Any process, either ADDITIVE or
SUBTRACTIVE, for producing color
photographs by the use of three
PRIMARY COLORS.
A statistically determined point
or region along some dimension
where sensory judgments occur
TINTOMETER
See LOVIBOND COLOR SYSTEM
TOE [4]
The portion of the characteristic
curve below the STRAIGHT-LINE
SECTION of the curve that
represents the area of minimum
useful exposure.
regarding the first-perceptibility TONE
or smallest perceived differences
of stimuli (e.g., colors). The overall perceptual effect of
a color or a colored photograph.
See Also: DIFFERENCE LIMEN
THRESHOLD, COLOR
See COLOR THRESHOLD
TIME-GAMMA CURVE [4]
A curve which indicates the
change in GAMMA obtained by
changes in time of DEVELOPMENT.
TIME-TEMPERATURE CHART [4]
A chart which indicates the
development times necessary at
various development temperatures
to produce approximately the
same degree of contrast.
TINT
(1) A very light, desaturated
color.
(2) To lightly color.
TINTING [5]
Coloring film by dyeing the
gelatin of the emulsion.
Note: For example, "The image has
a yellowish tone, a dark tone,
etc."
TONING [5]
Coloring a film by chemical
action on the silver image.
TOTAL COLOR BLINDNESS [5]
See MONOCHROMATISM
TRACK
The actual path of a collection
platform over the surface of the
earth.
TRANSFORMATION, COLOR COORDINATES
See COLOR COORDINATE
TRANSFORMATION
TRANSFORMATION OF COLOR-MIXTURE
DATA [51
COLOR-MIXTURE DATA for one set
of PRIMARIES can be used to
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TRANSFORMATION OF COLOR-MIXTURE
DATA [5] (Continued)
compute the color-mixture data
for any other set of primaries,
for the same observer. Such
computations are known as
Transformations of Color-Mixture
Data.
TRANSLUCENT [4]
A substance is translucent if it
allows light to pass through it
but interferes enough with the
passage of light to diffuse it
to a large degree. Ground and
opal glass, and thin paper are
Translucent.
TRANSMISSION [4]
The amount of radiant energy of
different wavelengths which a
filter, lens, or film will
transmit. Also called SPECTRAL
TRANSMISSION.
TRANSMISSION EFFICIENCY
A measure (0 to 100 percent) of
the ability of a medium to
transmit light. Low efficiency
means that light is lost by
absorption and reflection.
High efficiency, e.g. 90-100
percent, means that most of the
light is transmitted.
The loss of light during
transmission through a medium.
The INTERNAL TRANSMITTANCE for
a unit thickness of a
transmitting material.
See Also: TRANSMITTANCE, INTERNAL
The ratio of the transmitted
RADIANT or LUMINOUS FLUX to the
INCIDENT FLUX.
Note: Simply the ratio of the
amount of light coming out of a
medium to the amount entering it.
TRANSMITTANCE, INTERNAL
The ratio of light reaching the
the second surface of a medium
to the light that has just passed
through the first surface.
Note: in the Figure below, the
ratio of A to B.
TRANSMITTANCE, SPECTRAL
See SPECTRAL TRANSMITTANCE
TRANSMITTED FLUX
RADIANT FLUX that has passed
through a medium.
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TRANSPARENT [4]
A term describing any substance
which allows passage of light
without scattering; the opposite
of opaque.
(1) An image upon glass or film,
intended to be viewed by
transmitted light.
(2) A measure of the sample's
ability to transmit light without
scattering or diffusion or
degradation of its image forming
properties.
TRANSPARENCY RATIO [5]
The transparency ratio is the
ratio of the parallel trans-
mittance to the total trans-
mittance of the sample.
One who possesses TRICHROMATIC
VISION.
TRICHROMATIC COEFFICIENTS
See CHROMATICITY COORDINATES
TRICHROMATIC COLORIMETER
A COLORIMETER which uses mixtures
of three colors (usually red,
blue, and green) to match a
given sample.
TRICHROMATIC THEORY [5]
A color theory based on the facts
of trichromatic mixture, namely
that all hues may be derived from
the mixture of two or more of
the three PRIMARIES (usually
red, blue, and green).
The three inks used in making a
three-color print. They normally
correspond in color with the
SUBTRACTIVE PRIMARIES (CYAN,
MAGENTA, and YELLOW) but are
usually called blue, red, and
yellow.
TRICHROMATIC VISION
Same as Trichromatism.
THRICHROMATISM
A form of color vision yielding
colors which require, in general,
mixtures of three PRIMARIES
(such as red, green, and blue)
for their duplication. Normal
color vision (NORMAL TRICHROMAT)
or ANOMALOUS TRICHROMATISM are
considered this form of vision.
A composite filter containing
areas of three PRIMARY colors.
Any film consisting of three
sensitive layers in the EMULSION.
A type of theory which assumes
that color vision depends upon
the operation of three kinds of
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TRIRECEPTOR THEORY (Continued)
retinal receptors. Usually they
are CONES, each of which responds
to a different color, e.g. red,
blue, and green. All colors are
perceived because of the inter-
action of the three receptors.
See Also: YOUNG-HELMHOLTZ
COLOR VISION THEORY
TRITANOMALOUS VISION (TRITANOMALY;
a TRITAN)
A form of ANOMALOUS TRICHROMATISM
color deficiency which requires
more blue to match a blue-green
than normal. Also called blue-
weak vision.
TRITANOPIA (a TRITANOPE)
A type of DICHROMATIC VISION in
A COLORMETER using three or four which reddish-blue and greenish-
broad-band filters to provide yellow colors are confused with
measurements corresponding roughly gray and each other. Generally,
to the blue, green, and red blue is not perceived at all.
regions of the spectrum and (for
most instruments) are convertible Note: In the population it
by simple calculation to approx- affects approximately .002 per-
imate CIE TRISTIMULUS VALUES X, cent of males and .001 percent
Y, and Z. of females [6].
(1) See COLOR-MIXTURE DATA.
TRITANOPIA, SMALL AREA
Y, and Z are known as the A unit of visual stimulation
Tristimulus Values. Each is defined as the illuminance on the
found by integrating the area under RETINA which results when a
the curve resulting from the point surface luminance of 1 candela
(2) In the CIE COLOR SYSTEM, X,
by point multiplication of the
results of the SPECTRAL POWER
DISTRIBUTION curve of the
illuminant, times the SPECTRAL
TRANSMITTANCE or REFLECTANCE
curve of the color, times the
appropriate (x, y, or z) COLOR
MATCHING FUNCTION of the STANDARD
OBSERVER.
per square meter is incident
through an apparent pupil of 1
square millimeter area.
Note: The name of this unit has
been changed from photon to
Troland to avoid the confusion
caused by the subsequent physical
use of photon as a name for the
quantum of electromagnetic
radiation.
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The spreading of edges on imagery
caused by the diffusion of
exposing light in the emulsion.
The amount of diffusion depends
on the density and size of the
silver grains which reflect and
retract the exposing light.
TWO-COLOR PROCESS
Any process, either ADDITIVE or
SUBTRACTIVE, for producing color
photographs using only two colors.
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ULTRAVIOLET [5]
Radiant energy of wavelengths
shorter than extreme violet and
lying beyond the ordinarily
visible spectrum. Usually
assigned to wavelengths below
400 or 390 nanometers and
extending to below 200 nano-
meters.
ULTRAVIOLET ABSORBING FILTER [4]
A haze cutting filter used mainly
in photography with color films
to avoid excessive bluishness
and loss of contrast in the
pictures; usual designations are
U.V.; HAZE FILTER; Wratten 2A.
UNDERDEVELOPMENT [4]
approximate equally perceptible
steps of chromaticity.
A system in which pairs of
colors which are perceived as
being equally spaced are plotted
as being equally spaced.
Note: The primary aim of this
system is to transform the CIE
CHROMATICITY DIAGRAM so that
intervals on it are perceptually
equal. On such a diagram a
locus of points equidistant from
a center point would be percep-
tually equidistant from the
center point.
UNIFORM DIFFUSER [5]
Insufficient DEVELOPMENT, resulting; A surface having a total reflec-
in lack of density and./or contrast tion factor independent of the
(desaturated, washed-out colors); angle of illumination and having
caused by insufficient time in the LUMINANCE independent of the
solution, or weak developer. angle of view.
UNDEREXPOSE [4]
To allow insufficient light to Hues perceived as not having
reach the film or printing paper been mixed with adjacent SPECTRAL
for proper exposure. Underexposed COLORS. They are red, green,
color films are dark, very dense, yellow, and blue.
and lack detail.
UNIFORM-CHROMATICITY-SCALE COLOR
DIAGRAM
A color diagram resulting from a
COLOR COORDINATE TRANSFORMATION
of standard COLOR-MIXTURE DATA in.
which equal linear distances
See Also: PSYCHOLOGICAL PRIMARIES
UVEA
The CHOROID, CILIARY BODY, and
IRIS form the UVEA.
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VALUE [7] characteristics of the surround,
nature of the illuminant, etc.
In the MUNSELL COLOR SYSTEM it is
the expression of the LUMINOUS VIGNETTING [4]
REFLECTANCE (lightness) of an
object color on a scale of 0 A gradual reduction in density
(Black) to 10 (white) giving of parts (generally at the edges
approximately uniform perceptual and corners) of a photographic
steps under the usual conditions image caused by the stopping of
of observation. some of the rays entering the
Note: Munsell Value of an
opaque surface may (approximately)
be found by taking the cube
root of the LUMINOUS REFLECTANCE
according to the equation
V = 25Y1/3-17
lens. Thus, a lens mounting
may interfere with the extreme
oblique rays.
VILLALOBOS COLOUR ATLAS [6]
where V is Value and Y is Luminous A book of 7,279 glossy color
VALUE LEVEL [5]
A horizontal cross section
through the COLOR SOLID on which
all colors are of the same VALUE
or brightness.
VALUE SCALE [5]
A series of visually equidistant
neutral grays lying between
black and white.
VIEWING CONDITIONS [5]
a 4-mm hole in. each to facilitate
comparisons. There are 38 basic
colors and for each one there
are 19 series of colors. Within
a series each sample has approx-
imately the same daylight LUMINOUS
REFLECTANCE as the corresponding
gray. There are 20 such grays
from black to white. Each chip
is identified by a HUE letter, a
BRIGHTNESS VALUE, and a number
indicating the degree or
CHROMATICITY (uniform SATURATION
steps for a given HUE or
BRIGHTNESS VALUE).
VIOLET [5]
The hue attribute of visual
sensation t
i
ll
d b
k
y evo
yp
ca
e
y
The environmental conditions under
which a visual observation is made stimulation of the normal human
including the size of the stimulus, eye with shortwave radiation
around 433 nm and shorter.
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See VISION, FOVEAL: PARACENTRAL
VISION
VISION, FOVEAL [5]
Visual sensation or perception
caused by simulation of the
FOVEA CENTRALIS, which is nearly
100% CONES and is thus where color
perception and discrimination are
optimal.
VISION, INDIRECT
See VISION, PERIPHERAL
VISION, PERIPHERAL [5]
response to light in lower
organisms; the higher psychological
implications of light, color, form,
and their spatial and temporal
relations, etc. The anatomical and
physiological basis may be, to a
considerable extent, hypothetical,
as is the case with the current
theories of color vision.
Note: See Table 2 in the
Appendix.
The ability of the eye to
discriminate between fine
differences of visual detail.
VISUAL ADAPTATION
Visual sensation or perception due
to stimulation of outlying
portions of the retina or non-
FOVEAL VISION.
VISION, PERSISTENCE OF [5]
Adjustive change in visual
sensitivity caused by continued
visual stimulation or lack of
stimulation. Three recognized
types are (1) SCOTOPIC or DARK
ADAPTATION, (2) PHOTOPIC or
LIGHT ADAPTATION, and
(3) CHROMATIC or COLOR ADAPTATION.
changes in visual sensory response VISUAL ANGLE [5]
The tendency of visual excitation
to outlast the stimulus or, more
generally, the tendency of
to lag behind changes in the
stimulus.
VISION, THEORY OF [5]
A systematic attempt to account for
the various phenomena of visual
perception in relation to the
known structures and functions of
the visual organs. Included by
extension are the study of
photoreceptors; the action of
nerve-endings; related nervous
structures in general, the
The angle subtended by any object
of vision at the NODAL POINT of
the eye. The magnitude of this
angle determines the size of the
corresponding retinal image,
independent of the size or of
the distance of the object alone.
The nodal point is about 7 mm
behind the corneal surface and
about 17 mm in front of the
retina.
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VISUAL ANGLE [5] (Continued)
Note: The visual Angle 0 is See VISUAL DENSITY
usually approximated by measuring
d as in the Figure below. VISUAL SENSITIVITY [5]
D
The ratio of LUMINOUS FLUX to
RADIANT ENERGY FLUX.
Nodal point
of eye See Also: LUMINOSITY; LUMINOSITY
FACTOR; LUMINOUS EFFICIENCY
For the visual angle in radian, use
07= 57.3d
D
VISUAL SPECTRUM
See SPECTRUM
VISUAL TRISTIMULUS COLORIMETER
A COLORIMETER in which the
visual comparison field can be
d
d
d
juste
to pro
uce a continuous
A COLORIMETER in which the a
comparison color is adjusted until .,range of colors by modification
it visually matches the sample of three stimuli, usually red,
arison color is blue, and green lights.
color
The com
.
p
changed in steps or continuous,
depending on the type of
colorimeter.
See Also: VISUAL TRISTIMULUS
COLORIMETRY.
VISUAL DENSITY (LUMINOUS DENSITY)
The DENSITY of a medium as it
appears visually to the STANDARD
OBSERVER.
VITREOUS HUMOR [6]
A clear, viscous liquid
(specific viscosity in the range
of 1.8 to 2.0) which fills the
rear chamber of the eye between
the lens and the retina.
Note: See Figure 1 in the
Appendix.
Note: To measure the visual Color perceived as belonging to
density of a medium, a densitometer
is used which duplicates the human a definite tridimensional space
PHOTOPIC CURVE (y of the CIE 1931 or volume.
STANDARD OBSERVER).
Note: The volume mode of visual
appearance has the attribute of
transparency, e.g., colored
gelatin or jelly.
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VON KRIES COEFFICIENT LAW (6]
The color response functions
(x, y, z, of the STANDARD
OBSERVER) under one set of
adaptation conditions may be
considered proportional to the
response functions x', y', and
z' under another set of
adaptation conditions.
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WARM COLOR [5]
Any color which produces in the
observer a psychological reaction
or impression of apparent heat
is called a warm color, usually
red to orange.
WATT [4]
Unit of electrical power equal to
rate of work done by one ampere
under an electrical potential or
pressure of one volt.
The distance between corresponding
points on two successive waves,
applied particularly to electro-
magnetic radiations. These
radiations range in wavelength
sizes of a mile to a fraction of
a millionth-of-an-inch (X and
gamma rays). Wavelengths which
are visible are called LIGHT and
are measured in terms of the
following units (NANOMETERS is
preferred):
Micrometer (um) 1 pm = 10-3mm
Nanometer (nm) 1 nm = 10-6 mm
Angstrom (A) 1 A = 10-7mm
Note: Each wavelength may be
thought of as a particular color.
WAVELENGTH DISTRIBUTION
See SPECTRAL DISTRIBUTION
WEAK [4]
A term used to describe a print
or negative lacking density and
contrast.
WEAK COLOR [5]
A color of low saturation.
WEBER~FECHNER LAW [10]
The minimum difference in light
intensity which can be discrim-
inated DI bears a constancy
ratio to the intensity level I or
SI/I = k.
Note: This law does not hold
true and thus is considered an
approximation in the middle
ranges of intensity level.
WEDGE (STEP WEDGE, NEUTRAL DENSITY
WEDGE, OPTICAL WEDGE) [8]
In photography, a strip of
material - such as glass - covered
with a layer which is clear at one
end and becomes more and more
opaque towards the other end
(density range from 0 to 5 or 6).
Note: The layer itself may be a
dyed gelatin, a suspension of
pigment (such as carbon black) in
gelatin, or a developed silver
halide emulsion. The increase in
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WEDGE (STEP WEDGE, NEUTRAL DENSITY
WEDGE, OPTICAL WEDGE) [8] (Cont'd)
density may be smooth and contin-
uous or in regular sections. The
latter type is known as a STEP
WEDGE.
WEDGE SPECTROGRAM [8]
Note: For comparison, a BLACKBODY
absorbs all visible wavelengths.
In the OSTWALD COLOR SYSTEM it is
the amount of white in any color.
The record of the SPECTRAL
SENSITIVITY of a sensitized
material made by giving a series
of differing exposures to a
SPECTRUM projected on to it. In
practice the exposure scale is
produced by placing a neutral
density wedge over the sensitized
material in such a way that each
step of the wedge lies across the
whole projected spectrum. This
ensures that the material is
subjected to the full range of
exposures over every color.
A SPECTROPHOTOMETER which uses a
WEDGE to determine density.
(1) The ACHROMATIC COLOR
produced by emitting, reflecting,
or transmitting all wavelengths
of the visible spectrum equally
or nearly equally.
(2) The ACHROMATIC COLOR of
maximum lightness.
WHITE BODY [5]
A term applied to a SECONDARY
SOURCE which is nonabsorbing at
all visible wavelengths.
A color memory test in which the
examinee is required to look at
a colored test pattern and then
asked to choose from a set of
4 response patterns one or none
producing the same colors as the
test pattern.
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The CHROMATICITY COORDINATE in the
CIE COLOR SYSTEM for the x-axis of
the CHROMATICITY DIAGRAM.
The COLOR MATCHING FUNCTION in the
CIE COLOR SYSTEM.
The CIE TRISTIMULUS VALUE resulting
from using X.
The ordinate (x-axis) of the
CHROMATICITY DIAGRAM.
The numerical value for the x
CHROMATICITY COORDINATE.
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The CHROMATICITY COORDINATE in the (1) The hue attribute of visual
CIE System for the y-axis of the sensations typically evoked by
CHROMATICITY DIAGRAM. stimulation of the normal human
eye with radiation of wavelengths
approximately 577 nanometers.
The COLOR MATCHING FUNCTION in the (2) Any color manifesting a hue
CIE COLOR SYSTEM; the PHOTOPIC predominantly similar to that of
LUMINOSITY FUNCTION if the 1931 the typical yellow (wavelengths
CIE STANDARD OBSERVER is specified. 568 to 583).
(3) The COMPLEMENT of BLUE.
The CIE TRISTIMULUS VALUE resulting (4) The color resulting from the
from using y. mixtures of red and green lights.
See Also: MINUS-BLUE
The abscissa (y-axis) of the YELLOW DYE
CHROMATICITY DIAGRAM.
y-VALUE
The dye formed in the blue sensi-
tive layer of an emulsion.
The numerical value for the y
CHROMATICITY COORDINATE.
YAW [4]
(1) AIR NAVIGATION: The rotation
of an aircraft about its vertical
axis so as to cause the aircraft's
longitudinal axis to deviate from
the flight line. Sometimes called
CRAB.
Note: In positive transparencies
it is formed where blue wave-
lengths were not imaged; thus
stopping the transmission of blue
except where it was imaged. In
negatives it is formed where blue
wavelengths were imaged, thus
allowing its complement (YELLOW)
to be transmitted.
See Also: CYAN DYE; MAGENTA DYE
(2) PHOTOGRAMMETRY: The rotation YELLOW-GREEN
of a camera or a photograph
coordinate system about either the (1) The hue attribute of visual
photograph z axis or the exterior sensations typically evoked by
Z axis. In some photogrammetric stimulation of the normal retina
instruments and in analytical with radiation of wavelengths
applications, the symbol kappa (K) approximately 565 nm.
may be used.
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YELLOW-GREEN (Continued)
(2) The complement of Bluish-
Purple.
YELLOW-SIGHTED [5]
Characterizing a heightened color
sensitivity for yellow. or a
tendency to see all objects tinged
with yellow.
Note: The phenomenon occurs (1) in
individuals who possess a peculiar
pigmentation of certain tissues of
the eye, (2) in normal individuals
following blue-adaptation, or
(3) following the use of certain
drugs.
A theory which seeks to explain the
phenomena of color vision on the
assumption of three independent
component mechanisms (or processes)
in the retina or its attached
nervous apparatus; these mechanisms,
.when separately aroused (chiefly
by radiant energy of corresponding
regions in the spectrum) giving
rise to the colors, red, green,
and blue, respectively; all other
colors including yellow, purple,
and white or gray being due to
various combinations of the three
component activities.
Note: See Table 2 in the Appendix.
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The rarely used CHROMATICITY
COORDINATE for the z-axis of the
CHROMATICITY DIAGRAM.
The COLOR MATCHING FUNCTION in the
CIE Color System.
The CIE TRISTIMULUS VALUE resulting
from using E.
The numerical value for the z
CHROMATICITY COORDINATE.
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Fovea
Vitreous Optic
Disk
(Blind
Spot)
Retina--i
Optic
nerve
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Spectrum Locus
wavelength in nm
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Wavelength, nm
FIGURE 3. Spectral energy distribution
curves of skylight from different direc-
tions and under different conditions at
Cleveland, Ohio: (a) Zenith skylight,
(b) North skylight, (c) Entire overcast
sky, (d) Sun plus clear sky (daylight),
and (e) Direct sunlight [3].
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FIGURE 4. LIGHT UNITS [8]. A is
LUMINOUS INTENSITY, or the amount
of light emitted in all directions
by a candle made to standard
specifications. B is the light
source of one CANDELA. C is LUMINOUS
FLUX; the unit is the LUMEN. D is
ILLUMINANCE or the luminous flux per
unit area and is measured in LUX
(lumens per square meter). E is
REFLECTIVITY or the proportion of
the incident light reflected by a
surface. F is LUMINANCE or intensity
of light reflected by a surface,
measured in candela/square meter.
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Quantity
Multiply number of
By
To obtain number of
Luminous flux
light-watts
680
lumens
youngs
680
Illuminance
lumens/square meter
1
lumens/square centi-
104
meter
lux (lumen/meter2,
phot
104
lm/m2)
lumens/square foot
10.76
foot-candles
10.76
Luminance
stilb
104
foot lambert
3.426
3
2
lambert
3.183E-10
candelas/meter
(cd/m2
candle/ft2
10.76
meterlambert
1/II
(apostilb)
centimeterlambert
1/1IE+04
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TABLE 2. SUMMARY OF THE BETTER KNOWN
COLOR VISION THEORIES 16]
Name
A%natomieaI
I'undanten-
Relation to CIE
Chief Limitation
Location
tat Colors
Standard Observer
Young, three compo-
Cone pigments
Red
+3.1956.1 + 4.44781' - 0.6434Z
Fails to explain dichromatic vision as in-
nents
Green
-2.54551 + 7.049-2 1' + 0.4963Z
tended.
Violet
+ 5.000OZ
Helmholtz, three com-
Cone response
Red
+0.0701 + 0.945)' - 0.015Z
Fails to explain color perceptions of pro-
ponents
Green
-0.460X + 1.3591' + 0.1012
tauopes and deuteranopes.
Violet
+ 1.000Z
Dominator-modulator,
Cone response
Red
+ 1.0001'
Fails to explain color perceptions of pro-
late Konig
Green
-0.4601 + 1.3591' + 0.101Z
tanopes and deuteranopes.
Violet
+ 1.000Z
Ladd-Franklin, three
Cone response
Red
+3.76561 + 1.46351' - 0.22912
Implies that the blue function has a nega-
component.s, early
Green
-1.39731 + 6.12891' + 0.2683Z
tive luminosity for normals and deu-
Konig
Blue
+ 5.000OZ
teranopes, positive for protanopes.
Hering, opponent
Optic nerve
Red-green
+ 1.0(1131 - 1.000 Y
Fails to give an account of protanopia and
colors
Yellow-blue
+ 0.4001' - 0.400Z
tritanopia.
White-black
+ 1.0001'
Von Kries-Schro-
('one response
]led
+3.7656.0 + 1.4635)' - 0.22912
Implies that the blue function has a nega-
dinger. zone onstage
Green
-1.39731 + 6.1289Y + 0.26832
tive luminosity for normals and deu-
Blue
+ 3.000()Z
teranopes. positive for protanopes, fails
to give an account of tritanopia.
Optic nerve
Green-red
-3.537.V + 3.196) + 0.341Z
Blue-yellow
+1.341.0 - 5.884}' + 4.542Z
White-black
+ 1.()001'
Ilurvich-Jameson,
Receptor response
a
+ 6.53331' + 0.1333Z
I Requires frequency-shift of photosensi-
quantification of
6
-0.33331 + 7.00001'
tive spectral distribution functions to
Hering opponent
y
+0.33331 + 6.46671' - 0.1333Z
account for protanopia and tritanopia.
colors
Neural response "
lled-green
k2[1.0000X - 1.0000}'J
Yellow-blue
k1[0.4000}' - 0.4000Z]
White-black
(k3 - k4)[20.0000)'l
Adams, zone or stage
Cone pigments
Red
+3.19561 + 2.4478)' - 0.6434Z
Explanations of protanopia and tritan-
Green
-2.5455.1' + 7.04921' + 0.4963Z
opia based on subsidiary assumptions.
Violet
+ 5.000OZ
Cone response
Red
+1.0001
Green
+ 1.0001'
Blue
+ 1.000Z
Optic nerve "
Red-green
+1.000.0 - 1.0001'
Blue-yellow
- 0.4001' + 0.4002
White-black
+ 1.0001'
Muller, zone or stage
Cone pigments
Red
+3.1956.0 + 2.44781' - 0.64342
Implausible explanation of protanopic
Green
-2.5455X + 7.04941' + 0.49632
luminosity by resort to luminosity of
Violet
+ 5.000OZ
the yR cone response and luminosity-
inhibiting action of the bG cone re-
Cone response "
yR-bG
+5.7411 - 4.601)' - 1.140Z
sponse, both of which disappear with
y}'-rB
-0.9321 + 2.7501' - 1.8192
the yR-bG cone response to produce
Luminosity
+ 1.0001'
protanopia.
Optic nerve
Red-green
+6.345.1' - 6.3251'
Yellow-blue
+ 2.0041' - 2.004Z
White-black
+ 1.000 Y
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(1) Wyszecki, G. and Stiles, W. S., Color Science, 1st ed., John Wiley
and Sons, New York, 1967.
(2) Judd, D. B. and Wyszecki, G., Color in Business, Science and
Industry, 2nd ed., John Wiley and Sons, New York, 1963.
(3) Evans, R. M., An Introduction to Color, 1st ed., John Wiley and
Sons, New York, 1948.
(4) Manual of Color Aerial Photography, Editor John T. Smith, Jr.,
American Society of Photogrammetry, Arlington, Virginia, 1969.
(5) Comparative List of Color Terms, a Report, Compiled by Newhall, S. M.,
and Brennan, J. G., Inter-Society Color Council, Washington, D. C.,
1949.
(6) Burnham, R. W., Hanes, R. M., and Bartleson, C. J., Color: A Guide
to Basic Facts and Concepts, John Wiley and Sons, New York, 1963.
(7) Wintringham, W. T., "Color Television and Colorimetry", Proceedings
of the Institute of Radio Engineers, No. 39, pp?1135-1172.
(8) The Focal Encyclopedia of Photography, Focal Press, London-New York,
1965.
(9) Bennett, A. H., Glossary of Terms Frequently Used in Optics and
Spectroscopy, American Institute of Physics, New York, 1962.
(10) Evans, R. M., Hanson, W. T., and Brewer, W. L., Principles of Color
Photography, John Wiley and Sons, New York, 1953.
(11) Sowerby, L. M., Dictionary of Photography, 18th ed., Philisophical
Library, New York, 1957.
(12) Manual of Photogrammetry, 3rd ed., Thompson, M. M., Editor,
American Society of Photogrammetry, Arlington, Virginia, 1966.
(13) Optical Terms and Definitions, Military Standard, MIL-STD-1241A,
March 31, 1967.
(14) Glossary of Optical Terms, Bausch and Lomb (an unpublished pamphlet).
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(15) Judd, D. B., "Basic Correlates of the Visual Stimulus", in
Handbook of Experimental Psychology, Edited by S. S. Stevens,
John Wiley and Sons, New York, 1951.
(16) LeGrand, Y., Light Colour and Vision, 2nd ed., Chapman and Hall, Ltd.,
Ltd., London, 1968.
(17) Billmeyer, F. W. and Saltzman, M., Principles of Color Technology,
Interscience Pub.,. Div. of John Wiley and Sons, New York, 1966.
(18) Committee on Colorimetry, Optical Society of America, The Science
of Color, Thomas Y. Crowell Co., New York, 1953. Reported by the
Optical Society of America, 1963.
(19) Mees, C.E.K. and Jones, T. H., The Theory of the Photographic
Process, 3rd ed., The MacMillan Company, New York, 1966.
(20) American Society for Testing and Materials, 1970 Annual Book of
ASTM Standards, Index and Glossary, Part 33, November, ASTM,
Philadelphia, Pennsylvania, 1970.
(21) American Society for Testing and Materials, 1970 Annual Book of
ASTM Standards, General Testing Methods, Part 30, July, ASTM,
Philadelphia, Pennsylvania, 1970.
(22) American Society for Testing and Materials, "Nomenclature and
Definitions Applicable to Radiometric and Photometric Characteristics
of Matter", ASTM Special Publication No. 475, ASTM, Philadelphia,
Pennsylvania, 1970.
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