ASTM E284-22

Standard Terminology of Appearance

SIGNIFICANCE AND USE
3.1 This terminology standard contains definitions of appearance terms applicable to the work of many ASTM technical committees. Its use by committees other than Committee E12 on Color and Appearance, and its citation in the standards of such committees, is encouraged.  
3.2 In this terminology standard, definitions of terms used in other ASTM standards are indicated by placing the designation of that standard in parentheses at the end of the definition. Definitions used by other organizations (see Refs (3–4)) are indicated similarly by placing in parentheses at the end of the definition the acronym of the organization, occasionally with the date of its terminology standard quoted. In either case, a superscript letter may be used to indicate the degree of correspondence between the definition given herein and that in the citation. Superscript A indicates that the two are identical; B that the given definition is a modification of that cited, with little difference in essential meaning; and C that the two differ substantially.  
3.3 A further parenthetical inclusion at the end of the definition gives the revision, if after 1981, in which the definition was added to this terminology standard or last revised.  
3.4 Where appropriate, symbols or acronyms are listed for terms in this terminology standard. Since usage varies, these listings should be considered as recommendations, not as mandatory. If a different symbol or acronym is used in another ASTM standard, this should be indicated in that standard.  
3.5 In the 1990 edition of this terminology standard, a great many terms were relocated to conform to the recommendation of the Form and Style for ASTM Standards, (Blue Book) that listings be in spoken word order. In general, there are no cross-references between the old and new listings, except where a special function is served. An example of such a special function is to list all terms relating to a given basic quantity, for example, all terms defining various ...
SCOPE
1.1 This terminology standard defines terms used in the description of appearance, including but not limited to color, gloss, opacity, scattering, texture, and visibility of both materials (ordinary, fluorescent, retroreflective) and light sources (including visual display units).  
1.2 It is the policy of ASTM Committee E12 on Color and Appearance that this terminology standard include important terms and definitions explicit to the scope, whether or not the terms are currently used in an ASTM standard. Terms that are in common use and appear in common-language dictionaries (see Refs (1–2)2) are generally not included, except when the dictionaries show multiple definitions and it seems desirable to indicate the definitions recommended for E12 standards.  
1.3 The usage of terms describing appearance varies considerably. In some cases, different usage of a term in different fields has been noted.  
1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

General Information

• Status: Published
• Publication Date: 30-Sep-2022
• ICS: 17.040.20 - Properties of surfaces
• Technical Committee: E12 - Color and Appearance
• Drafting Committee: E12.01 - Terminology

Relations

• Refers: ASTM D883-24 - Standard Terminology Relating to Plastics
• Effective Date: 01-Feb-2024
• Refers: ASTM D16-24 - Standard Terminology for Paint, Related Coatings, Materials, and Applications
• Effective Date: 01-Jan-2024
• Refers: ASTM E808-23 - Standard Practice for Describing Retroreflection
• Effective Date: 01-Dec-2023
• Refers: ASTM E2214-23 - Standard Practice for Specifying and Verifying the Performance of Color-Measuring Instruments
• Effective Date: 01-Dec-2023
• Refers: ASTM E1164-23 - Standard Practice for Obtaining Spectrometric Data for Object-Color Evaluation
• Effective Date: 01-Nov-2023
• Refers: ASTM D883-23 - Standard Terminology Relating to Plastics
• Effective Date: 01-Nov-2023
• Refers: ASTM D156-23 - Standard Test Method for Saybolt Color of Petroleum Products (Saybolt Chromometer Method)
• Effective Date: 01-Oct-2023
• Refers: ASTM E456-13a(2022)e1 - Standard Terminology Relating to Quality and Statistics
• Effective Date: 01-Apr-2022
• Refers: ASTM D1129-13(2020)e2 - Standard Terminology Relating to Water
• Effective Date: 01-May-2020
• Refers: ASTM E2214-20 - Standard Practice for Specifying and Verifying the Performance of Color-Measuring Instruments
• Effective Date: 01-May-2020
• Refers: ASTM C242-20 - Standard Terminology of Ceramic Whitewares and Related Products
• Effective Date: 01-Feb-2020
• Refers: ASTM E135-20 - Standard Terminology Relating to Analytical Chemistry for Metals, Ores, and Related Materials
• Effective Date: 01-Jan-2020
• Refers: ASTM D883-20 - Standard Terminology Relating to Plastics
• Effective Date: 01-Jan-2020
• Refers: ASTM D1695-07(2019) - Standard Terminology of Cellulose and Cellulose Derivatives
• Effective Date: 01-Dec-2019
• Refers: ASTM E349-06(2019)e1 - Standard Terminology Relating to Space Simulation
• Effective Date: 01-Oct-2019

Overview

ASTM E284-22: Standard Terminology of Appearance provides standardized definitions for terms related to the appearance properties of materials and light sources, including color, gloss, opacity, texture, and visibility. Developed by ASTM Committee E12 on Color and Appearance, this standard is designed to ensure consistent communication and interpretation of appearance-related terminology across various industries and technical committees. The standard is especially important for professionals involved in materials science, quality control, color measurement, coatings, textiles, and visual display technologies.

Standardized appearance terminology is essential for objective evaluation, specification, and comparison of products and materials worldwide. ASTM E284-22 is widely referenced and encourages adoption across all relevant ASTM committees, not just E12, promoting harmonization of language in the fields of color science and appearance measurement.

Key Topics

The standard covers fundamental terms and concepts related to the visual properties of objects and materials, including:

• Color: Attributes such as hue, chroma, and lightness; color measurement methods; visual and instrumental color comparisons.
• Gloss: Definitions regarding specular and diffuse reflection, gloss units, and conditions influencing gloss perception.
• Opacity: Terms describing the amount of light transmission and hiding power of materials, crucial for coatings and packaging.
• Scattering: Describes how light interacts with surfaces and particles, affecting appearance.
• Texture: Definitions related to surface features that impact visual characteristics or tactile perception.
• Visibility: Concepts involving the detectability and legibility of materials or displays under various lighting conditions.
• Retroreflectance & Fluorescence: Terms used in safety, signage, and high-visibility materials.
• Terminological conventions: Guidance on acronyms, symbols, and citation of definitions from other ASTM standards and organizations.
• Revision and cross-referencing: Documentation of when definitions are added, updated, and how they correspond to other international standards.

Applications

The terminology provided in ASTM E284-22 is critical for a range of practical applications:

• Material and product specification: Used by manufacturers to describe and control the appearance of paints, plastics, papers, textiles, ceramics, and metals.
• Quality Assurance: Ensures consistency in the evaluation of appearance characteristics across supply chains and laboratories.
• Color and appearance measurement: Supports the standardized use of instruments such as spectrophotometers, colorimeters, gloss meters, and retroreflection testers.
• Industry standards integration: Facilitates the development and revision of other ASTM standards by providing a consistent vocabulary.
• Research and development: Assists scientists and engineers in clearly communicating their findings.
• International trade and regulatory compliance: Aligns with World Trade Organization principles for reducing technical barriers through standardized terminology.

Related Standards

ASTM E284-22 references and is aligned with several other important standards, including:

• ASTM D1535: Practice for Specifying Color by the Munsell System
• ASTM E1164: Practice for Obtaining Spectrometric Data for Object-Color Evaluation
• ASTM D1003: Test Method for Haze and Luminous Transmittance of Transparent Plastics
• ISO 13655: Spectral Measurement and Colorimetric Computation for Graphic Arts Images
• ASTM D16, D123, D883: Terminology standards for coatings, textiles, and plastics
• CIE standards: International Commission on Illumination publications for color measurement and daylight simulation

By referencing ASTM E284-22, organizations ensure their appearance descriptions and measurement protocols are based on internationally recognized, harmonized terminology, supporting interoperability and clear communication in global markets.

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: E284 − 22
Standard Terminology of
Appearance
This standard is issued under the fixed designation E284; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
INTRODUCTION
Appearance, including the appearance of objects, materials, and light sources, is of importance in
many arts, industries, and scientific disciplines.Appearance terms are used in a wide range ofASTM
standards as well as other documents of concern in standardization, testing, and specification. The
purpose of this terminology standard is to define terms relating to the description of appearance.
Definitions are of two distinctly different kinds. A descriptive definition reports existing usage,
whereas a prescriptive definition is an invitation to use a term in a specific way. By agreement of
ASTM Committee E12 on Color and Appearance, the definitions in this terminology standard are
taken to be prescriptive in nature. Committee E12 thereby assumes a position of leadership in usage.
Terms and definitions in several terminology standards and vocabularies other than ASTM (see
References),aswellasotherASTMterminologystandards,havebeenconsideredforinclusioninthis
terminology standard.An effort has been made to achieve greater accuracy, brevity, clarity, precision,
and internal consistency, and to draw distinctions that are useful in the practical measurement and
specification of appearance.
Suggestions for additions or revisions to this terminology standard are welcome.
1. Scope 1.4 This international standard was developed in accor-
dance with internationally recognized principles on standard-
1.1 This terminology standard defines terms used in the
ization established in the Decision on Principles for the
description of appearance, including but not limited to color,
Development of International Standards, Guides and Recom-
gloss, opacity, scattering, texture, and visibility of both mate-
mendations issued by the World Trade Organization Technical
rials (ordinary, fluorescent, retroreflective) and light sources
Barriers to Trade (TBT) Committee.
(including visual display units).
2. Referenced Documents
1.2 It is the policy of ASTM Committee E12 on Color and
Appearance that this terminology standard include important 3
2.1 ASTM Standards:
terms and definitions explicit to the scope, whether or not the
C242Terminology of Ceramic Whitewares and Related
terms are currently used in anASTM standard. Terms that are
Products
in common use and appear in common-language dictionaries
C286 Terminology Relating to Porcelain Enamel and
(see Refs (1–2) ) are generally not included, except when the
Ceramic-Metal Systems
dictionariesshowmultipledefinitionsanditseemsdesirableto
C460TerminologyforAsbestos-Cement(Withdrawn2001)
indicate the definitions recommended for E12 standards.
D16TerminologyforPaint,RelatedCoatings,Materials,and
Applications
1.3 The usage of terms describing appearance varies con-
D123Terminology Relating to Textiles
siderably. In some cases, different usage of a term in different
D156Test Method for Saybolt Color of Petroleum Products
fields has been noted.
(Saybolt Chromometer Method)
D883Terminology Relating to Plastics
This terminology is under the jurisdiction of ASTM Committee E12 on Color
and Appearance and is the direct responsibility of Subcommittee E12.01 on
Terminology. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Oct. 1, 2022. Published December 2022. Originally contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
approved in 1966. Last previous edition approved in 2017 as E284–17. DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/E0284-22. the ASTM website.
2 4
The boldface numbers in parentheses refer to a list of references at the end of The last approved version of this historical standard is referenced on
text. www.astm.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E284 − 22
D1003Test Method for Haze and Luminous Transmittance TAPPI T 452Brightness of Pulp, Paper, and Paperboard
of Transparent Plastics (Directional Reflectance at 457 nm)
D1129Terminology Relating to Water
3. Significance and Use
D1245Practice for Examination of Water-Formed Deposits
3.1 This terminology standard contains definitions of ap-
by Chemical Microscopy
pearance terms applicable to the work of manyASTM techni-
D1535Practice for Specifying Color by the Munsell System
cal committees. Its use by committees other than Committee
D1695Terminology of Cellulose and Cellulose Derivatives
E12 on Color andAppearance, and its citation in the standards
D1889Test Method for Turbidity of Water (Withdrawn
4 of such committees, is encouraged.
2007)
3.2 Inthisterminologystandard,definitionsoftermsusedin
D2805Test Method for Hiding Power of Paints by Reflec-
otherASTMstandardsareindicatedbyplacingthedesignation
tometry
of that standard in parentheses at the end of the definition.
E131Terminology Relating to Molecular Spectroscopy
Definitions used by other organizations (see Refs (3–4)) are
E135Terminology Relating to Analytical Chemistry for
indicated similarly by placing in parentheses at the end of the
Metals, Ores, and Related Materials
definition the acronym of the organization, occasionally with
E179Guide for Selection of Geometric Conditions for
the date of its terminology standard quoted. In either case, a
Measurement of Reflection and Transmission Properties
superscript letter may be used to indicate the degree of
of Materials
correspondence between the definition given herein and that in
E313Practice for Calculating Yellowness and Whiteness
the citation. Superscript A indicates that the two are identical;
Indices from Instrumentally Measured Color Coordinates
B that the given definition is a modification of that cited, with
E349Terminology Relating to Space Simulation
little difference in essential meaning; and C that the two differ
E456Terminology Relating to Quality and Statistics
substantially.
E491Practice for Solar Simulation for Thermal Balance
3.3 A further parenthetical inclusion at the end of the
Testing of Spacecraft
definition gives the revision, if after 1981, in which the
E808Practice for Describing Retroreflection
definition was added to this terminology standard or last
E809Practice for Measuring Photometric Characteristics of
revised.
Retroreflectors
3.4 Where appropriate, symbols or acronyms are listed for
E903Test Method for Solar Absorptance, Reflectance, and
terms in this terminology standard. Since usage varies, these
Transmittance of Materials Using Integrating Spheres
listings should be considered as recommendations, not as
E1164PracticeforObtainingSpectrometricDataforObject-
mandatory. If a different symbol or acronym is used in another
Color Evaluation
ASTM standard, this should be indicated in that standard.
E1767Practice for Specifying the Geometries of Observa-
tion and Measurement to Characterize the Appearance of 3.5 In the 1990 edition of this terminology standard, a great
many terms were relocated to conform to the recommendation
Materials
of the Form and Style for ASTM Standards, (Blue Book) that
E2175Practice for Specifying the Geometry of Multiangle
listings be in spoken word order. In general, there are no
Spectrophotometers
cross-references between the old and new listings, except
E2214Practice for Specifying and Verifying the Perfor-
where a special function is served. An example of such a
mance of Color-Measuring Instruments
special function is to list all terms relating to a given basic
F923Guide to Properties of High Visibility Materials Used
quantity, for example, all terms defining various sorts of
to Improve Individual Safety (Withdrawn 2006)
angles.
2.2 Other Documents:
3.6 Thisterminologystandardadoptsthefollowingusageof
ANSI PH2.36Terms, Symbols, and Notation for Optical
certainwordendings.Theending“ion”denotesaprocess,asin
Transmission and Reflection Measurement (Optical Den-
reflection; “ance” denotes a property of a specimen, as in
sity)
reflectance;and“ity”denotesapropertyofthekindofmaterial
CIE Publication No. 51AMethod forAssessing the Quality
of which the specimen is composed, as in reflectivity. Excep-
of Daylight Simulators for Colorimetry
tionsexist,asinthecommonuseof illuminationand radiation
ISO 13655Spectral Measurement and Colorimetric Compu-
to refer to quantities as well as processes.
tation for Graphic Arts Images
ISO 3664:2000Viewing Conditions – Graphic Technology 4. Terminology
and Photography
4.1 Definitions:
AATCC blue wool lightfastness standards, n—standard
dyed-wool samples of seven grades, each step in the series
representing a doubling of lightfastness.
Available fromAmerican National Standards Institute (ANSI), 25 W. 43rd St.,
4th Floor, New York, NY 10036, http://www.ansi.org.
Available from CIE (International Commission on Illumination), http://
www.cie.co.at or http://techstreet.com. Available from Technological Association of the Pulp and Paper Industry
Available from International Organization for Standardization (ISO), 1 rue de (TAPPI), 15 Technology Parkway South, Suite 115, Peachtree Corners, GA30092,
Varembé, Case postale 56, CH-1211, Geneva 20, Switzerland, http://www.iso.ch. http://www.tappi.org.
E284 − 22
DISCUSSION—Available from the American Association of Textile
stimuli in such a manner that they cannot be perceived
A
Chemists and Colorists.
individually. (1995a) [CIE]
abridged spectrophotometry, n—the measurement of reflec-
additive primaries, n—same as primary color stimuli.
tance factor or transmittance factor in a number of wave-
ambient field, n—whenanobjectorlightsourceisviewed,the
length bands rather than as continuous functions of wave-
complete area beyond the surround from which light might
length.
reach the observer’s eyes and influence the object’s appear-
DISCUSSION—The wavelength bands may be isolated by the use of an
ance. See surround.
array of sensors with a dispersing system or by the use of narrow-band
filters.
American Public Health Association (APHA) color, n—see
absorbance, A, n—logarithmtothebase10ofthereciprocalof platinum cobalt color scale.
the internal transmittance T. A=log (1/T)=−log T.
angle, n—see aperture angle, aperture solid angle, azi-
I 10 I 10 I
B
(1990) (E131)
muthal angle, entrance angle, observation angle, rotation
angle, specular angle.
absorptance α, n—the ratio of the absorbed radiant or lumi-
A
angle of illumination, n—angle between the specimen normal
nous flux to the incident flux. [CIE]
and the illuminator axis. (1991b)
absorption, n—the transformation of radiant energy to a
A
angle of incidence, n—the angle between a ray impinging on
different form of energy by interaction with matter. [CIE]
a surface at a point and the perpendicular to the surface at
absorption coefficient, α, n—measure of the absorption of
that point. In the description of a beam, the angle of
radiant energy from an incident beam (P ) as it traverses an
o
incidence of the ray at the center of the beam.
−αb
absorbing medium according to Bouguer’s law, P = Poe ,
where b is the sample optical pathlength. (1988) (E131) angle of reflection, n—the angle between a ray reflected from
a surface at a point and the perpendicular to the surface at
absorption tinting strength, n—relativechangeintheabsorp-
that point.
tion properties of a standard white material when a specified
amount of an absorbing colorant, black or chromatic, is
angle of view, n—angle between the normal to the surface of
added to it. (1988a)
the specimen and the axis of the receiver and (1988a); see
DISCUSSION—See the Discussion to masstone.
also viewing angle (2). (2013)
absorptivity, a, n—the absorbance divided by the product of
angle, rotation, n—see rotation angle.
the concentration, c, of the substance and the sample optical
angular subtense, n—visual, the angle subtended (by an
pathlength, b, a = A⁄bc. The units of b and c shall be
object) at the first nodal point of the eye.
B
specified. (1988) (E131)
annular, adj—descriptor for directional illuminating (or view-
accuracy, n—the closeness of agreement between a test result
ing)geometryinwhichtheilluminatorprovidesradiation(or
and an accepted reference value. (1993)
the receiver possesses responsivity) that is distributed con-
DISCUSSION—The qualitative term accuracy, when applied to a set of
tinuously and uniformly throughout the 360° of azimuth of
observed values, will be a combination of a random precision compo-
the measurement. (See also circumferential.) (1989)
nent and a systematic error or bias component. Since in routine use
A
random components and bias components cannot be completely
(E1164)
separated,thereported“accuracy”mustbeinterpretedasacombination
of these two elements. See bias, precision. anormal, adj—of angles, measured with reference to the
normal to the surface. (2008)
achromatic, adj—(1) for primary light sources, the computed
chromaticity of the equal-energy spectrum. (1995)
anormal angle, n—the angle subtended at a point on the
specimen by a given ray and the normal. (2009)
achromatic, adj—(2) for surface colors, the color of a whitish
DISCUSSION—Use the inward normal with transmitted rays; use the
light, serving as the illuminant, to which adaptation has
outward normal for other rays. In uniplanar instruments, the “point” is
taken place in the visual system of the observer. (1995)
the point of incidence and the anormal angle is understood to have a
sign.The anormal angle of an illumination axis is positive or zero.The
achromatic, adj—(3) perceived as having no hue, that is, as
B anormal angle of a detection axis is negative if the illumination and
white, gray, or black. [CIE]
detection axes are on opposite sides of the line of the normal and
C C
positive or zero otherwise. (E1767) ,(E2175)
Adams color difference, n—color difference calculated by
usingtheAdams-Nickersonopponent-colorequations,based
aperture angle, 2κ, n—angle subtended at a point on a
on applying the Munsell Value function to CIE 1931
specimen by the maximum dimension of the illuminator or
tristimulus values X, Y, Z. (1988)
receiver, within which the flux in a directional beam is
additive color mixture, n—superposition or other nondestruc- contained. (1990)
tive combination of lights of different perceived colors. DISCUSSION—In optics, the symbolκ is used for the half angle; hence
the recommended symbol here is 2κ.
(1995)
additive color stimulus mixture, n—method of simulation aperture mode, n—color seen through an aperture which
that combines on the retina the actions of various color prevents its association with a specific object or source.
E284 − 22
aperture solid angle,ω,n—solidanglesubtendedatapointon basic color terms, n—a group of eleven color names found in
the specimen, defined by the sum of rays from the illumi- anthropological surveys to be in wide use in fully developed
nator or the sum of directions in which the receiver is languages: white, black, red, green, yellow, blue, brown,
sensitive to incoming radiation. (1990) gray, orange, purple, pink. (1990)
aperture stop, n—the physical diameter that limits the size of beam, n—in optics, a concentrated unidirectional flow of
the cone of radiation that an optical system will accept from radiant energy. (1988)
A
an axial point on the object. (1988) [OSA]
Beer’s law, n—the absorbance of a homogeneous sample
appearance, n—(1) of an object,thecollectedvisualaspectsof containing an absorbing substance is directly proportional to
an object or a scene. (2006b) the concentration of the absorbing substance. See also
A
absorptivity. (1988) (E131)
appearance, n—(2) perceived, the visual perception of an
object, including size, shape, color, texture, gloss, bias, n—a systematic difference between the sample mean of
the measurements or test results and an accepted reference
transparency, opacity, etc., separately or integrated. (2006b)
value. (1993)
area reflector, n—reflector subtending a relatively large solid
DISCUSSION—Bias is the systematic component of accuracy. There
angle at the observer’s eye, so that the observer can clearly
may be one or more systematic error components contributing to the
distinguish its size and shape. (1988)
bias. In appearance measurement, the accepted reference value is
usually assigned to a standard specimen; see physical standard.
artificial daylight, n—an artificial light that has a spectral
biconical, adj—see the preferred but not equivalent term,
power distribution approximating that of a phase of natural
bidirectional, as in bidirectional optical measuring system.
daylight. (1995)
(1991b)
aspecular, adj—of angles, measured with reference to the
bidirectional, adj—see bidirectional optical measuring sys-
specular direction. (2008)
tem. (1991)
bidirectional optical measuring system, n—anopticalsystem
aspecular angle, n—the angle subtended at the point of
for measuring the reflecting or transmitting properties of
incidence by a given ray and the specular direction. (2009)
specimens, wherein the illuminator and receiver each sub-
DISCUSSION—In instruments, the “given ray” is understood to be a
detection direction. In uniplanar instruments, the aspecular angle is to tend small angles at the specimen surface. (1988a)
be understood to have a sign: negative when the specular direction lies
bidirectional scattering distribution function (BSDF),
properly between the detection direction and the illuminator axis and
C C
n—for a uniformly-illuminated surface, the distribution with
positive otherwise. (E1767) ,(E2175)
respect to the scatter direction of the average surface
attributes of color, adj—(1) for the object mode of
radiance divided by the surface irradiance when that surface
appearance, hue, lightness, and saturation. In the Munsell
is illuminated in a specified direction. (2006a)
system, Munsell Hue, Munsell Value, and Munsell Chroma.
DISCUSSION—BSDF is a differential function dependent on the
wavelength,incidentdirection,scatterdirection,andpolarizationstates
attributes of color, adj—(2) for the illuminant or aperture
of the incident and scattered fluxes. The BSDF is equivalent to the
mode, hue, brightness, and saturation.
fractionoftheincidentfluxscatteredperunitprojectedsolidangle.The
BSDF of a lambertian surface is independent of scatter direction. The
azimuthal angle,η, n—anglebetweentheplanecontainingthe
BSDFofaspecularlyreflectingsurfacehasasharppeakinthespecular
axis of the illuminator (or the path of illumination) and the
direction. Each measurement of BSDF obtains an average of the local
specimen normal and the plane containing the axis of the
BSDF at points within the measurement aperture. If a surface scatters
receiver (or the path of reception) and the specimen normal.
non-uniformly from one position to another then a series of measure-
The origin and direction of measure of the angle should be ments over the sample surface must be averaged to obtain a suitable
statistical uncertainty.
specified when required. (1990)
bispectral fluorescence radiance factor, b (µ), n—the ratio
azimuthal viewing, n—deprecated term; do not use. Replace F
λ
of the spectral radiance at wavelength λ due to fluorescence
azimuthal by annular or circumferential. (1995a)
from a point on the specimen when irradiated at wavelength
banding, n—a non-uniformity of color appearance on a scale
µ to the total radiance of the perfectly reflecting diffuser
much larger than colorant particles, characterized by a band
similarly irradiated and viewed (see NPLReport MOM 12).
or several nearly parallel indistinct stripes differing slightly
bispectral radiance factor, b (µ), n—the ratio of the spectral
in color from the remaining area. λ
radiance (radiance per unit waveband) at wavelength λ from
bandpass, adj—having to do with a passband. (2006)
apointonaspecimenwhenirradiatedatwavelength µtothe
total (integrated spectral) radiance of the perfectly reflecting
bandwidth, n—the width of a passband at its half-peak
diffuser similarly irradiated and viewed.
transmittance. (2006)
b ~µ! 5 L ~µ!/L~µ! (1)
λ λ d
barré, n—a defect characterized by bars or streaks, fillingwise
in woven fabrics or coursewise in weft-knit fabrics, caused bispectral reflection radiance factor, b (µ), n—the ratio of
Rλ
by uneven tension in knitting, or defective yarn, improper the spectral radiance at wavelength λ due to reflection from
needle action, or other similar factors. a point on the specimen when irradiated at wavelength µ to
E284 − 22
thetotalradianceoftheperfectlyreflectingdiffusersimilarly calibrate, v—to find and eliminate systematic errors of an
irradiated and viewed. instrument scale or method of measurement by use of
material standards and techniques traceable to an authorized
bispectrometer, n—an optical instrument equipped with a
national or international measurement system. (1994a)
source of irradiation, two monochromators, and a detection
DISCUSSION—As defined here, calibration is normally carried out by
system, such that a specimen can be measured at
an instrument manufacturer. See standardize, verify.
independently-controlled irradiation and viewing wave-
candela, cd, n—theSIunitofluminousintensity;theluminous
lengths.The bispectrometer is designed to allow for calibra-
intensity, in a given direction, of a source that emits
tion to provide quantitative determination of the bispectral
monochromatic radiation of frequency 540×10 hertz and
radiation-transfer properties of the specimen. (5)
that has a radiant intensity in that direction of (1/683) watt
DISCUSSION—Typically, a reference detection system monitors the
per steradian.
radiation incident on the specimen. This reference detection system
serves to compensate for both temporal and spectral variations in the DISCUSSION—The lone frequency of 540×10 Hz mentioned in the
fluxincidentuponthespecimen,bynormalizationofreadingsfromthe definition has a wavelength of 555.016 nm in standard air, which for
instrument’s emission detection system. almost all purposes can be taken to be 555 nm without affecting the
accuracy of a real measurement. For sources at other frequencies
blackbody, n—see the preferred term, full radiator.
(wavelengths), scale their spectral radiant intensities by the spectral
A
bleached specimen, n—specimenwhoseabsorptancehasbeen luminous efficiency function, V(λ). [CIE]
A
decreased by chemical or radiant means. (1987) [TAPPI]
centroid wavelength, n—wavelength marking the center, in
bleeding, n—theunintentionaltransferofcoloringmatterfrom terms of area under a curve, of a function of wavelength
one medium to or through another.
weighted by multiplication with a specified response func-
tion. (1988)
bloom, n—thescatteringoflightindirectionsnearthespecular
DISCUSSION—In the case of (TAPPI) brightness (of paper) the
angle of reflection by a deposit on or exudation from a
response function is obtained by the use of a special blue tristimulus-
specimen.
colorimeter filter.
blur, n—unsharpness (of an image). (2006)
characterize, v—to specify the parameters or performance of
DISCUSSION—Blur may result from effects of motion, defocus,
an instrument or method of measurement. (1994)
diffraction, or other factors.
DISCUSSION—For example, in appearance measurement, the param-
eters might include the geometric and spectral nature of the illuminator
blur, vt—to make (an image) less sharp. (2006)
and the receiver, and the performance might be specified by measures
of reliability, precision, and bias.
body color, n—color produced by absorption and scattering of
light by colorants within a colored material. (1988)
chatoyance, n—appearance characterized by a changeable
luster or color, sometimes including a spatially-undulating
Bouguer’s law, n—the absorbance of a homogeneous sample
narrow white band or stripe.
is directly proportional to the thickness of the sample in the
optical path. (Also known as Lambert’s [thickness] law.)
chemical luminescence, n—luminescence resulting from a
A
(1988) (E131)
chemical reaction. (See also luminescence.)
brightness, n—aspect of visual perception whereby an area
chroma, n—(1)attributeofcolorusedtoindicatethedegreeof
B B
appearstoemitmoreorlesslight.(1995) [CIE] (F923) departure of the color from a neutral color of the same
lightness. See also Munsell chroma. (1989b)
brightness, n—of an object color, combination of lightness
and saturation.
chroma, n—(2) C*, (in the CIE 1976 L*, a*, b*or L*, u*, v*
2 2 1/2
system) the quantity C* =(a* + b* ) or
ab
brightness, n—in the textile industry, perceived as saturated,
2 2 1/2
C* =(u* + v* ) . (1989b).
uv
vivid, deep, or clean.
DISCUSSION—ThisusagemayconflictwithDefinition2inthecaseof
chroma, n—(3) attribute of a visual perception, produced by
dark colors.
an object color, that permits a judgment to be made of the
amount of pure chromatic color present, irrespective of the
brightness, n—of paper, reflectance of an infinitely thick
amount of achromatic color. (1995)
specimen (reflectivity) measured for blue light with a cen-
DISCUSSION—See also saturation, Definition (2).
troid wavelength of 457 nm under specified spectral and
geometric conditions of measurement. (1987) [TAPPI
chromatic, adj—perceived as having a hue; not white, gray, or
B
T 452]
black.
brightness, n—dyer’s, the color quality, combining lightness chromatic adaptation, n—changes in the visual system’s
and saturation, that would be decreased by adding black,
sensitivities due to changes in the spectral quality of illumi-
gray, or a complementary color to a chromatic dye. nating and viewing conditions. (1988)
bronzy color (or bronzing), n—ametalliccolorationobserved chromaticity, n—the color quality of a color stimulus defin-
when viewing the light reflected at angles near the angle of able by its chromaticity coordinates, or by its dominant (or
specular reflection, the color usually being quite different complementary) wavelength and its purity taken together.
A
from that observed for other directions. [CIE]
E284 − 22
chromaticity coordinates, n—theratioofeachofthetristimu- CIE standard illuminant A, n—colorimetric illuminant, rep-
lusvaluesofanyviewedlighttothesumofthethree.(1995) resenting the full radiator at 2855.6 K, defined by the CIE in
B
DISCUSSION—Chromaticity coordinates in the CIE 1931 system of terms of a relative spectral power distribution. [CIE]
color specification are designated by x, y, z and in the CIE 1964
CIE standard illuminant B, n—colorimetric illuminant, rep-
supplementary system x , y , z .)
10 10 10
resenting direct sunlight with a correlated color temperature
chromaticity diagram, n—a plane diagram in which points
of 4874 K, defined by the CIE in terms of a relative spectral
specified by chromaticity coordinates represent the chroma-
power distribution. Declared obsolete by the CIE in 1983.
B
ticities of lights (color stimuli). (1995) [CIE]
(1988)
chromaticness, n—(1) attribute of visual perception combin-
CIE standard illuminant C, n—colorimetric illuminant, rep-
ing the hue and saturation. (1995)
resenting daylight with a correlated color temperature of
6774 K, defined by the CIE in terms of a relative spectral
chromaticness, n—(2) attribute of a visual perception accord-
B
power distribution. [CIE]
ing to which the color of an area appears to be more or less
chromatic. (1995) CIE standard illuminant D , n—colorimetric illuminant,
DISCUSSION—The term colorfulness is sometimes used as a synonym
representing daylight with a correlated color temperature of
B B
for Definition (2). [CIE, 1970] [CIE, 1987]
6504 K, defined by the CIE in terms of a relative spectral
B
power distribution. (1987) [CIE]
CIE, n—the abbreviation for the French title of the Interna-
tional Commission on Illumination, Commission Interna- CIE 1931 standard observer, n—ideal colorimetric observer
tionale de l’Éclairage. with color matching functions x¯(λ), y¯(λ), z¯(λ) corresponding
to a field of view subtending a 2° angle on the retina;
CIE color-rendering index, R, n—measure of the degree to B
commonly called the “2° standard observer.” (1988) [CIE]
which the computed chromaticity of a CIE test color sample
CIE standard source A, n—a gas-filled tungsten-filament
illuminated by a test illuminant conforms to that of the same
lampoperatedatacorrelatedcolortemperatureof2855.6K.
sample illuminated by a reference illuminant. (1995)
B
[CIE]
DISCUSSION—For eight CIE test-color samples, the results are CIE
special color-rendering indices, R, i=1–8. The average of these is the
i
C CIE standard source B, n—standard sourceAcombined with
CIE general color-rendering index R . [CIE]
a
a specified liquid filter, to provide radiant flux with a
CIE primaries, n—the primary color stimuli used in the CIE correlated color temperature of 4874 K. Declared obsolete
system of colorimetry. by the CIE in 1983. (1988)
CIE standard source C, n—standard sourceAcombined with
CIE spectral tristimulus values, n—tristimulus values or
a specified liquid filter, to provide radiant flux with a
color-matching functions of the spectral components of an
B
correlated color temperature of 6774 K. (1988) [CIE]
equal-energy spectrum in the CIE (XYZ) system. (1990)
DISCUSSION—The color matching functions are assigned the symbols
CIE 1964 supplementary standard colorimetric system,
x¯(λ), y¯(λ), z¯(λ) in the CIE 1931 colorimetric system and x¯ (λ), y¯ (λ),
10 10
B n—a system for determining the tristimulus values of any
z¯ (λ) in the CIE 1964 supplementary colorimetric system. [CIE]
spectral power distribution using the set of reference color
CIE 1931 (x,y) chromaticity diagram, n—chromaticity dia- stimuli X , Y , Z , and the three CIE color-matching
10 10 10
gram for the CIE 1931 standard observer, in which the CIE functions x¯ (λ), y¯ (λ), z¯ (λ) adopted by the CIE in 1964.
10 10 10
A
1931chromaticitycoordinatesareplotted,with xasabscissa (1989) [CIE]
and y as ordinate. (1993)
CIE 1964 supplementary standard observer, n—ideal colo-
rimetric observer with color matching functions x¯ (λ),
CIE 1964 (x ,y ) chromaticity diagram, n—chromaticity
10 10
y¯ (λ), z¯ (λ) corresponding to a field of view subtending a
diagram for the CIE 1964 supplementary standard observer,
10 10
10° angle on the retina; commonly called the “10° standard
in which the CIE 1964 chromaticity coordinates are plotted,
B
observer.” (1988) [CIE]
with x as abscissa and y as ordinate. (1993)
10 10
CIE 1976 uniform-chromaticity-scale diagram, n—the
CIE 1976 (u',v')or (u' , v' ) chromaticity diagram,
10 10
uniform-chromaticity-scale diagram produced by plotting in
n—chromaticity diagram in which the CIE 1976 L* u* v*
rectangular coordinates v'against u', quantities defined as
(CIELUV) chromaticity coordinates are plotted, with u'(or
follows:
u' ) as abscissa and v'(or v' ) as ordinate. (1993)
10 10
DISCUSSION—These chromaticity diagrams should be used when
u' 5 4X/ X115Y13Z 5 4x/ 22x112y13 (2)
~ ! ~ !
diagrams more nearly equally visually spaced than the (x, y)or
(x ,y ) diagrams are desired.
v' 5 9Y/ X115Y13Z 5 9y/ 22x112y13
10 10 ~ ! ~ !
CIE 1931 standard colorimetric system, n—a system for for the CIE 1931 standard colorimetric system, or v'
determining the tristimulus values of any spectral power against u' for the CIE 1964 supplementary standard colori-
distribution using the set of reference color stimuli X, Y, Z metric system, in which case in the above formulae X , Y ,
10 10
and the three CIE color-matching functions x¯(λ), y¯(λ), z¯(λ) Z are used instead of X, Y, Z and x , y instead of x, y.
10 10 10
A A
adopted by the CIE in 1931. (1987) [CIE] (1987) [CIE]
E284 − 22
CIELAB color difference, n—color difference calculated by coefficient of retroreflection, R , n—of a plane reflecting
A
using the CIE 1976 L* a* b* opponent-color scales, based surface,theratioofthecoefficientofluminousintensity(R)
I
on applying a cube-root transformation to CIE 1931 tris- of a plane retroreflecting surface to its area (A), expressed in
−1 −2
timulus values X, Y, Z or CIE 1964 tristimulus values X , candelasperluxpersquaremetre(cd·lx ·m ). R =(R/A).
10 A I
A
Y , Z . (1988) (1988) (E808)
10 10
collector, n—optical components, such as the cornea and lens
CIELUV color difference, n—color difference calculated by
of the eye, which guide radiant flux from a specimen being
usingtheCIE1976L*u*v*opponent-colorscales,basedon
observed or measured to a sensor.
a linear transformation of CIE chromaticity coordinates x, y,
DISCUSSION—A collector and a sensor comprise a receiver.
or x , y and a cube-root transformation of Y or Y to L*,
10 10 10
applied to CIE 1931 tristimulus values X, Y, Z or CIE 1964
color, n—(1) of an object, aspect of object appearance distinct
tristimulus values X , Y , Z . (1988)
from form, shape, size, position, or gloss that depends upon
10 10 10
the spectral composition of the incident light, the spectral
circumferential, adj—descriptor for directional illuminating
reflectance or transmittance of the object, and the spectral
(or viewing) geometry in which the illuminator provides
response of the observer, as well as the illuminating and
radiation (or the receiver possesses responsivity) in many
viewing geometry. (1987)
beams (or directions), normally distributed at uniform inter-
vals throughout the 360° of azimuth of the measurement. color, n—(2) perceived, attribute of visual perception that can
The number and angular distribution of the beams (or
be described by color names such as white, gray, black,
directions) should be specified. (See also annular.) (1990) yellow, brown, vivid red, deep reddish purple, or by combi-
A
(E1164)
nations of such names.
DISCUSSION—Perceived color depends greatly on the spectral power
circumjacent field, n—the field surrounding the field of
distribution of the color stimulus, but also on the size, shape, structure,
interest extending in all directions. (2012)
and surround of the stimulus area, the state of adaptation of the
DISCUSSION—The circumjacent field may be either a background or a
observer’s visual system, and the observer’s experience with similar
A
surround. In art:Asurround is an area that touches the object, or object
observations. [TAPPI]
field, on all sides and will strongly affect its appearance.Abackground
color, n—(3) colorimetric, characteristics of a color stimulus
passes behind the object, or object field, and is further from it and so
has a smaller effect on the appearance of the object or object field. denoted by a colorimetric specification with three values,
(2013)
such as tristimulus values.
DISCUSSION—Tristimulus values are sometimes derived on a relative
clarity, n—the characteristic of a transparent body whereby
rather than an absolute basis. In this case they may need to be
distinct high-contrast images or high-contrast objects (sepa-
supplemented by the value of a suitable absolute photometric quantity.
rated by some distance from the body) are observable
Theappearanceofcolorsdependsnotonlyontheirabsolutetristimulus
through the body. values, but also on the conditions under which they are viewed,
including the nature of the surround; however, colors having the same
cmc (l:c) color difference, n—color difference calculated by
absolute tristimulus values appear the same in identical viewing
use of the formula developed by the Colour Measurement
conditions. Spectrally different color stimuli can have the same
A B
Committee of the Society of Dyers and Colourists of Great
absolute tristimulus values. [TAPPI] [CIE]
Britain. (1990)
color angle, n—in measurement of gonioapparent phenomena,
DISCUSSION—Based on the lightness, hue, chroma version of
halftheanglebetweentheilluminationanddetectionaxesof
CIELAB, it incorporates chroma and hue-angle correction terms for
the measurement geometry. (2008)
improvedvisualspacingandvariableweightingfactorsforlightness(l)
DISCUSSION—The color of an interference pigment is determined by
and chroma (c) relative to hue for improved correlation depending on
the angle of incidence of the light relative to the normal of the
typeofjudgment(acceptability,perceptibility)andapplication(textiles,
interference pigment flake. Flakes in a coating have an angular
others).
distribution, and the interference effect will be exhibited in a given
coefficient of line retroreflection,R ,n—ofareflectingstripe, measurement geometry only by the flakes that are oriented so that they
M
behaveasspecularreflectors.Sincetherefractiveindexofthespecimen
the ratio of the coefficient of luminous intensity (R)ofa
I
isoftenunknown,colorangleisdefinedhereasiftheflakeswereinair.
retroreflecting stripe to its length (l), expressed in candelas
−1 −1 A Colorangleprovidesarelativeindicationoftheanglebetweentheflake
per lux per metre (cd·lx ·m ). R =(R/l). (1988) (E808)
M I
normal and the illuminator axis.
coefficient of luminous intensity R , n—of a retroreflector,
I
colorant, n—dye, pigment, or other agent used to impart a
ratio of the luminous intensity (I) of the retroreflector in the
color to a material. (1988)
direction of observation to the illuminance (E )atthe
'
color atlas, n—a collection of color samples arranged accord-
retroreflector on a plane perpendicular to the direction of the
−1
ing to a color order system. (1990)
incident light, expressed in candelas per lux (cd·lx ).
A
R =(I/E ). (1988) (E808)
color constancy, n—the general tendency of the colors of an
I '
object to remain constant when the color of the illumination
coefficient of retroreflected luminance, R , n—ratio of the
L
is changed.
luminance, L, of a projected surface to the normal
illuminance, E , at the surface on a plane normal to the color difference, n—(1) perceived, the magnitude and charac-
'
incidentlight,expressedincandelaspersquaremetreperlux ter of the difference between two colors described by such
−2 −1 B
(cd·m ·lx ). R =(L/E ). (1988) (E808) terms as redder, bluer, lighter, darker, grayer, or cleaner.
L '
E284 − 22
color difference, n—(2) computed, the magnitude and direc- color notation, n—the symbols used in a systematic way to
tion of the difference between two psychophysical color designate colors.
stimuli and their components computed from tristimulus
color order system, n—a rational method or plan of ordering
values,orchromaticitycoordinatesandluminancefactor,by
and specifying all producible object or display colors, or all
means of a specified set of color-difference equations.
within a limited domain, by means of a set of physical
standards selected and displayed so as to represent ad-
color-difference units, n—unitsofsizeofthecolordifferences
equately the whole set of such colors under consideration.
calculated according to various equations. Such color differ-
(1990)
ences cannot be accurately converted between different
equations by the use of average factors. (1988)
color perception, n—subjective impression of color, as modi-
fied by the conditions of observation and by mental inter-
colorfulness, n—see chromaticness (2). (1991a)
A
pretation of the stimulus object. (1987) [TAPPI]
color grading, n—the act of identifying a specimen by a color
grade or color score, which is specific to the color and the
color preference, n—preference, within a specific application,
material graded.
for one color over other related colors. (1988)
DISCUSSION—Examples include preferred blue for sky or green for
colorimeter, n—see tristimulus colorimeter, visual colorim-
grass in photographic color reproduction, and preferred white for bond
eter.
paper.
colorimetric purity, p , n—thefractionofspectrallypurelight
c
color rendering, n—effect of a light source on the color
in an additive mixture with reference achromatic (white)
appearances of objects compared to their color appearances
light to produce a color that matches that of the color
under a reference light source. (See also CIE color render-
stimulus considered. (As a reference achromatic light, the
ing index.) (1988)
CIE recommends an equal energy source for self-luminous
bodies and illuminant D (daylight) for nonself-luminous
color scale, n—see Gardner color scale, petroleum color
B
bodies.) [CIE]
scale, platinum-cobalt color scale, Saybolt color.
color solid, n—see color space. (1987)
colorimetry, n—the science of color measurement.
color space, n—a geometric space, usually of three
dimensions, in which colors are arranged systematically.
color match, n—(1) condition existing when colors match
within a specified or agreed tolerance. Sometimes called
color specification, n—notation or set of three color-scale
commercial color match. (1988a)
values used to designate a color in a specified color system.
DISCUSSION—Compliance with tolerances can be determined instru-
Practicalcolorspecificationsmayincludecolortolerancesas
mentally or visually. If the test for compliance is visual, physical color
well as target color designation. (1988)
tolerance standards may be used for reference.
color staining, n—thediscolorationofamaterialbytransferof
color match, n—(2) condition existing when colors are indis-
C
colorant from another material. (D123)
tinguishable; a normal observer is usually implied. Some-
times called an exact color match. (1988a).
color stimulus, n—a radiant flux capable of producing a color
perception. (1995)
color matching, n—procedure for providing, by selection,
formulation, adjustment, or other means, a trial color that is color stimulus function, φ(λ), n—description of a color
stimulus by the spectral concentration of a radiometric
indistinguishable from, or within specified tolerances of, a
specified standard color under specified conditions. (1988a) quantity, such as radiance or radiant power, as a function of
wavelength.
color-matching functions, n—the amounts, in any trichro-
DISCUSSION—Compare with spectral power distribution. Unlike a
matic system, of the three reference color stimuli needed to
spectral power distribution, a color stimulus function is specific to flux
A
matchbyanadditivemixturemonochromaticcomponentsof
that is seen by the eye. [CIE]
an equal energy spectrum.
color temperature, n—of a source, the temperature, usually
DISCUSSION—Symbolsforthesefunctionsarelowercaseletters,each
expressed in kelvins, of a full radiator that would emit light
with a bar above and followed by the Greek letterλ in parentheses; the
of the same chromaticity as the source. (See also correlated
lower case letters corresponding to the capital letter symbols for the
B
¯
color temperature, distribution temperature.) [CIE]
referencecolorstimuliofthesystem;forexample, r¯(λ), g¯(λ), b(λ)inan
RGB system, x¯(λ), y¯(λ), z¯(λ), in the CIE 1931 XYZ colorimetric system,
color tolerance, n—the permissible color difference between
and x¯ (λ), y¯ (λ), z¯ (λ), in the CIE 1964 supplementary system which
10 10 10
sample and specified color.
is based on the 10° field of view.
color tolerance set, n—a group of colored standards, usually
color measurement, n—process of deriving, by visual or
seven painted chips, arranged on a single card, one exhibit-
instrumental means, a set of three numbers that describe the
ing a desired color, and two each exhibiting the limits of the
attributes of a color, in the form of a color notation or a
permissible range of color variation in each of the color
colorimetric specification. (1988)
attributes.
color mixture, n—see additive color mixture, additive color
DISCUSSION—Anexampleisonedesiredcolor,twolimitsonMunsell
stimulus mixture, or subtractive color mixture. value, two limits on Munsell hue, and two limits on Munsell chroma.
E284 − 22
complementary color percepts, n—(1)pairsofcolorpercepts, daylight illuminant, n—illuminant having the same, or nearly
one of which is induced by the other through simultaneous the same, relative spectral power distribution as a phase of
A
contrast. daylight. (1987) [CIE]
complementary color percepts, n—(2)pairsofcolorpercepts, densitometer, n—instrument designed for measuring optical
one of which is the negative after-image of the other.
density of a photographic negative or positive or a printed
A
image. (1987) [TAPPI]
complementary colors, n—color stimuli t
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: E284 − 17 E284 − 22
Standard Terminology of
Appearance
This standard is issued under the fixed designation E284; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
INTRODUCTION
Appearance, including the appearance of objects, materials, and light sources, is of importance in
many arts, industries, and scientific disciplines. Appearance terms are used in a wide range of ASTM
standards as well as other documents of concern in standardization, testing, and specification. The
purpose of this terminology standard is to define terms relating to the description of appearance.
Definitions are of two distinctly different kinds. A descriptive definition reports existing usage,
whereas a prescriptive definition is an invitation to use a term in a specific way. By agreement of
ASTM Committee E12 on Color and Appearance, the definitions in this terminology standard are
taken to be prescriptive in nature. Committee E12 thereby assumes a position of leadership in usage.
Terms and definitions in several terminology standards and vocabularies other than ASTM (see
References), as well as other ASTM terminology standards, have been considered for inclusion in this
terminology standard. An effort has been made to achieve greater accuracy, brevity, clarity, precision,
and internal consistency, and to draw distinctions that are useful in the practical measurement and
specification of appearance.
Suggestions for additions or revisions to this terminology standard are welcome.
1. Scope*Scope
1.1 This terminology standard defines terms used in the description of appearance, including but not limited to color, gloss,
opacity, scattering, texture, and visibility of both materials (ordinary, fluorescent, retroreflective) and light sources (including visual
display units).
1.2 It is the policy of ASTM Committee E12 on Color and Appearance that this terminology standard include important terms and
definitions explicit to the scope, whether or not the terms are currently used in an ASTM standard. Terms that are in common use
and appear in common-language dictionaries (see Refs (1–2) ) are generally not included, except when the dictionaries show
multiple definitions and it seems desirable to indicate the definitions recommended for E12 standards.
1.3 The usage of terms describing appearance varies considerably. In some cases, different usage of a term in different fields has
been noted.
1.4 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
This terminology is under the jurisdiction of ASTM Committee E12 on Color and Appearance and is the direct responsibility of Subcommittee E12.01 on Terminology.
Current edition approved May 1, 2017Oct. 1, 2022. Published July 2017December 2022. Originally approved in 1966. Last previous edition approved in 20132017 as
E284 – 13b.E284 – 17. DOI: 10.1520/E0284-17.10.1520/E0284-22.
The boldface numbers in parentheses refer to a list of references at the end of text.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E284 − 22
2. Referenced Documents
2.1 ASTM Standards:
C242 Terminology of Ceramic Whitewares and Related Products
C286 Terminology Relating to Porcelain Enamel and Ceramic-Metal Systems
C460 Terminology for Asbestos-Cement (Withdrawn 2001)
D16 Terminology for Paint, Related Coatings, Materials, and Applications
D123 Terminology Relating to Textiles
D156 Test Method for Saybolt Color of Petroleum Products (Saybolt Chromometer Method)
D883 Terminology Relating to Plastics
D1003 Test Method for Haze and Luminous Transmittance of Transparent Plastics
D1129 Terminology Relating to Water
D1245 Practice for Examination of Water-Formed Deposits by Chemical Microscopy
D1535 Practice for Specifying Color by the Munsell System
D1695 Terminology of Cellulose and Cellulose Derivatives
D1889 Test Method for Turbidity of Water (Withdrawn 2007)
D2805 Test Method for Hiding Power of Paints by Reflectometry
E131 Terminology Relating to Molecular Spectroscopy
E135 Terminology Relating to Analytical Chemistry for Metals, Ores, and Related Materials
E179 Guide for Selection of Geometric Conditions for Measurement of Reflection and Transmission Properties of Materials
E313 Practice for Calculating Yellowness and Whiteness Indices from Instrumentally Measured Color Coordinates
E349 Terminology Relating to Space Simulation
E456 Terminology Relating to Quality and Statistics
E491 Practice for Solar Simulation for Thermal Balance Testing of Spacecraft
E808 Practice for Describing Retroreflection
E809 Practice for Measuring Photometric Characteristics of Retroreflectors
E903 Test Method for Solar Absorptance, Reflectance, and Transmittance of Materials Using Integrating Spheres
E1164 Practice for Obtaining Spectrometric Data for Object-Color Evaluation
E1767 Practice for Specifying the Geometries of Observation and Measurement to Characterize the Appearance of Materials
E2175 Practice for Specifying the Geometry of Multiangle Spectrophotometers
E2214 Practice for Specifying and Verifying the Performance of Color-Measuring Instruments
F923 Guide to Properties of High Visibility Materials Used to Improve Individual Safety (Withdrawn 2006)
2.2 Other Documents:
ANSI PH2.36 Terms, Symbols, and Notation for Optical Transmission and Reflection Measurement (Optical Density)
CIE Publication No. 51 A Method for Assessing the Quality of Daylight Simulators for Colorimetry
ISO 13655 Spectral Measurement and Colorimetric Computation for Graphic Arts Images
ISO 3664:2000 Viewing Conditions – Graphic Technology and Photography
TAPPI T 452 Brightness of Pulp, Paper, and Paperboard (Directional Reflectance at 457 nm)
3. Significance and Use
3.1 This terminology standard contains definitions of appearance terms applicable to the work of many ASTM technical
committees. Its use by committees other than Committee E12 on Color and Appearance, and its citation in the standards of such
committees, is encouraged.
3.2 In this terminology standard, definitions of terms used in other ASTM standards are indicated by placing the designation of
that standard in parentheses at the end of the definition. Definitions used by other organizations (see Refs (3–4)) are indicated
similarly by placing in parentheses at the end of the definition the acronym of the organization, occasionally with the date of its
terminology standard quoted. In either case, a superscript letter may be used to indicate the degree of correspondence between the
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
The last approved version of this historical standard is referenced on www.astm.org.
Available from American National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036, http://www.ansi.org.
Available from CIE (International Commission on Illumination), http://www.cie.co.at or http://techstreet.com.
Available from International Organization for Standardization (ISO), 1 rue de Varembé, Case postale 56, CH-1211, Geneva 20, Switzerland, http://www.iso.ch.
Available from Technological Association of the Pulp and Paper Industry (TAPPI), 15 Technology Parkway South, Suite 115, Peachtree Corners, GA 30092,
http://www.tappi.org.
E284 − 22
definition given herein and that in the citation. Superscript A indicates that the two are identical; B that the given definition is a
modification of that cited, with little difference in essential meaning; and C that the two differ substantially.
3.3 A further parenthetical inclusion at the end of the definition gives the revision, if after 1981, in which the definition was added
to this terminology standard or last revised.
3.4 Where appropriate, symbols or acronyms are listed for terms in this terminology standard. Since usage varies, these listings
should be considered as recommendations, not as mandatory. If a different symbol or acronym is used in another ASTM standard,
this should be indicated in that standard.
3.5 In the 1990 edition of this terminology standard, a great many terms were relocated to conform to the recommendation of the
Form and Style for ASTM Standards, (Blue Book) that listings be in spoken word order. In general, there are no cross-references
between the old and new listings, except where a special function is served. An example of such a special function is to list all
terms relating to a given basic quantity, for example, all terms defining various sorts of angles.
3.6 This terminology standard adopts the following usage of certain word endings. The ending “ion” denotes a process, as in
reflection; “ance” denotes a property of a specimen, as in reflectance; and “ity” denotes a property of the kind of material of which
the specimen is composed, as in reflectivity. Exceptions exist, as in the common use of illumination and radiation to refer to
quantities as well as processes.
4. Terminology
4.1 Definitions:
AATCC blue wool lightfastness standards, n—standard dyed-wool samples of seven grades, each step in the series
representing a doubling of lightfastness.
DISCUSSION—
Available from the American Association of Textile Chemists and Colorists.
abridged spectrophotometry, n—the measurement of reflectance factor or transmittance factor in a number of wavelength
bands rather than as continuous functions of wavelength.
DISCUSSION—
The wavelength bands may be isolated by the use of an array of sensors with a dispersing system or by the use of narrow-band filters.
absorbance, A,n—logarithm to the base 10 of the reciprocal of the internal transmittance T .A = log (1/T ) = −log T . (1990)
I 10 I 10 I
B
(E131)
A
absorptance α,n—the ratio of the absorbed radiant or luminous flux to the incident flux. [CIE]
A
absorption, n—the transformation of radiant energy to a different form of energy by interaction with matter. [CIE]
absorption coefficient, α,n—measure of the absorption of radiant energy from an incident beam (P ) as it traverses an absorbing
o
−αb
medium according to Bouguer’s law, P = Poe , where b is the sample optical pathlength. (1988) (E131)
absorption tinting strength, n—relative change in the absorption properties of a standard white material when a specified
amount of an absorbing colorant, black or chromatic, is added to it. (1988a)
DISCUSSION—
See the Discussion to masstone.
absorptivity, a,n—the absorbance divided by the product of the concentration, c, of the substance and the sample optical
B
pathlength, b, a = A ⁄bc. The units of b and c shall be specified. (1988) (E131)
accuracy, n—the closeness of agreement between a test result and an accepted reference value. (1993)
DISCUSSION—
The qualitative term accuracy, when applied to a set of observed values, will be a combination of a random precision component and a systematic error
E284 − 22
or bias component. Since in routine use random components and bias components cannot be completely separated, the reported “accuracy” must be
interpreted as a combination of these two elements. See bias, precision.
achromatic, adj—(1) for primary light sources, the computed chromaticity of the equal-energy spectrum. (1995)
achromatic, adj—(1) for primary light sources, the computed chromaticity of the equal-energy spectrum. (1995)
(2) ) for surface colors, the color of a whitish light, serving as the illuminant, to which adaptation has taken place in the visual
system of the observer. (1995)
B
(3) perceived as having no hue, that is, as white, gray, or black. [CIE]
B
achromatic, adj—(3) perceived as having no hue, that is, as white, gray, or black. [CIE]
Adams color difference, n—color difference calculated by using the Adams-Nickerson opponent-color equations, based on
applying the Munsell Value function to CIE 1931 tristimulus values X, Y, Z. (1988)
additive color mixture, n—superposition or other nondestructive combination of lights of different perceived colors. (1995)
additive color stimulus mixture, n—method of simulation that combines on the retina the actions of various color stimuli in
A
such a manner that they cannot be perceived individually. (1995a) [CIE]
additive primaries,n—same as primary color stimuli.
ambient field, n—when an object or light source is viewed, the complete area beyond the surround from which light might reach
the observer’s eyes and influence the object’s appearance. See surround.
American Public Health Association (APHA) color,n—see platinum cobalt color scale.
angle,n—see aperture angle, aperture solid angle, azimuthal angle, entrance angle, observation angle, rotation angle,
specular angle.
angle of illumination, n—angle between the specimen normal and the illuminator axis. (1991b)
angle of incidence, n—the angle between a ray impinging on a surface at a point and the perpendicular to the surface at that
point. In the description of a beam, the angle of incidence of the ray at the center of the beam.
angle of reflection, n—the angle between a ray reflected from a surface at a point and the perpendicular to the surface at that
point.
angle of view, n—angle between the normal to the surface of the specimen and the axis of the receiver and (1988a); see also
viewing angle (2). (2013)
angle, rotation,n—see rotation angle.
angular subtense, n—visual, the angle subtended (by an object) at the first nodal point of the eye.
annular, adj—descriptor for directional illuminating (or viewing) geometry in which the illuminator provides radiation (or the
receiver possesses responsivity) that is distributed continuously and uniformly throughout the 360° of azimuth of the
A
measurement. (See also circumferential.) (1989) (E1164)
anormal, adj—of angles, measured with reference to the normal to the surface. (2008)
E284 − 22
anormal angle, n—the angle subtended at a point on the specimen by a given ray and the normal. (2009)
DISCUSSION—
Use the inward normal with transmitted rays; use the outward normal for other rays. In uniplanar instruments, the “point” is the point of incidence
and the anormal angle is understood to have a sign. The anormal angle of an illumination axis is positive or zero. The anormal angle of a detection
C
axis is negative if the illumination and detection axes are on opposite sides of the line of the normal and positive or zero otherwise. (E1767) ,
C
(E2175)
aperture angle, 2κ,n—angle subtended at a point on a specimen by the maximum dimension of the illuminator or receiver,
within which the flux in a directional beam is contained. (1990)
DISCUSSION—
In optics, the symbol κ is used for the half angle; hence the recommended symbol here is 2κ.
aperture mode, n—color seen through an aperture which prevents its association with a specific object or source.
aperture solid angle, ω,n—solid angle subtended at a point on the specimen, defined by the sum of rays from the illuminator
or the sum of directions in which the receiver is sensitive to incoming radiation. (1990)
aperture stop, n—the physical diameter that limits the size of the cone of radiation that an optical system will accept from an
A
axial point on the object. (1988) [OSA]
appearance, n—(1) of an object, the collected visual aspects of an object or a scene. (2006b)
appearance, n—(1) of an object, the collected visual aspects of an object or a scene. (2006b)
(2) perceived, the visual perception of an object, including size, shape, color, texture, gloss, transparency, opacity, etc.,
separately or integrated. (2006b)
area reflector, n—reflector subtending a relatively large solid angle at the observer’s eye, so that the observer can clearly
distinguish its size and shape. (1988)
artificial daylight, n—an artificial light that has a spectral power distribution approximating that of a phase of natural daylight.
(1995)
aspecular, adj—of angles, measured with reference to the specular direction. (2008)
aspecular angle, n—the angle subtended at the point of incidence by a given ray and the specular direction. (2009)
DISCUSSION—
In instruments, the “given ray” is understood to be a detection direction. In uniplanar instruments, the aspecular angle is to be understood to have a
C
sign: negative when the specular direction lies properly between the detection direction and the illuminator axis and positive otherwise. (E1767) ,
C
(E2175)
attributes of color, adj—(1) for the object mode of appearance, hue, lightness, and saturation. In the Munsell system, Munsell
Hue, Munsell Value, and Munsell Chroma.
(2) for the illuminant or aperture mode, hue, brightness, and saturation.
attributes of color, adj—(2) for the illuminant or aperture mode, hue, brightness, and saturation.
azimuthal angle, η,n—angle between the plane containing the axis of the illuminator (or the path of illumination) and the
specimen normal and the plane containing the axis of the receiver (or the path of reception) and the specimen normal. The origin
and direction of measure of the angle should be specified when required. (1990)
E284 − 22
azimuthal viewing, n—deprecated term; do not use. Replace azimuthal by annular or circumferential. (1995a)
banding, n—a non-uniformity of color appearance on a scale much larger than colorant particles, characterized by a band or
several nearly parallel indistinct stripes differing slightly in color from the remaining area.
bandpass, adj—having to do with a passband. (2006)
bandwidth, n—the width of a passband at its half-peak transmittance. (2006)
barré, n—a defect characterized by bars or streaks, fillingwise in woven fabrics or coursewise in weft-knit fabrics, caused by
uneven tension in knitting, or defective yarn, improper needle action, or other similar factors.
basic color terms, n—a group of eleven color names found in anthropological surveys to be in wide use in fully developed
languages: white, black, red, green, yellow, blue, brown, gray, orange, purple, pink. (1990)
beam, n—in optics, a concentrated unidirectional flow of radiant energy. (1988)
Beer’s law, n—the absorbance of a homogeneous sample containing an absorbing substance is directly proportional to the
A
concentration of the absorbing substance. See also absorptivity. (1988) (E131)
bias, n—a systematic difference between the sample mean of the measurements or test results and an accepted reference value.
(1993)
DISCUSSION—
Bias is the systematic component of accuracy. There may be one or more systematic error components contributing to the bias. In appearance
measurement, the accepted reference value is usually assigned to a standard specimen; see physical standard.
biconical,adj—see the preferred but not equivalent term, bidirectional, as in bidirectional optical measuring system. (1991b)
bidirectional,adj—see bidirectional optical measuring system. (1991)
bidirectional optical measuring system, n—an optical system for measuring the reflecting or transmitting properties of
specimens, wherein the illuminator and receiver each subtend small angles at the specimen surface. (1988a)
bidirectional scattering distribution function (BSDF), n—for a uniformly-illuminated surface, the distribution with respect to
the scatter direction of the average surface radiance divided by the surface irradiance when that surface is illuminated in a
specified direction. (2006a)
DISCUSSION—
BSDF is a differential function dependent on the wavelength, incident direction, scatter direction, and polarization states of the incident and scattered
fluxes. The BSDF is equivalent to the fraction of the incident flux scattered per unit projected solid angle. The BSDF of a lambertian surface is
independent of scatter direction. The BSDF of a specularly reflecting surface has a sharp peak in the specular direction. Each measurement of BSDF
obtains an average of the local BSDF at points within the measurement aperture. If a surface scatters non-uniformly from one position to another then
a series of measurements over the sample surface must be averaged to obtain a suitable statistical uncertainty.
bispectral fluorescence radiance factor, b (μ), n—the ratio of the spectral radiance at wavelength λ due to fluorescence from
F
λ
a point on the specimen when irradiated at wavelength μ to the total radiance of the perfectly reflecting diffuser similarly
irradiated and viewed (see NPL Report MOM 12).
bispectral radiance factor, b (μ), n—the ratio of the spectral radiance (radiance per unit waveband) at wavelength λ from a
λ
point on a specimen when irradiated at wavelength μ to the total (integrated spectral) radiance of the perfectly reflecting diffuser
similarly irradiated and viewed.
b μ 5 L μ /L μ (1)
~ ! ~ ! ~ !
λ λ d
E284 − 22
bispectral reflection radiance factor, b (μ), n—the ratio of the spectral radiance at wavelength λ due to reflection from a point
Rλ
on the specimen when irradiated at wavelength μ to the total radiance of the perfectly reflecting diffuser similarly irradiated and
viewed.
bispectrometer, n—an optical instrument equipped with a source of irradiation, two monochromators, and a detection system,
such that a specimen can be measured at independently-controlled irradiation and viewing wavelengths. The bispectrometer is
designed to allow for calibration to provide quantitative determination of the bispectral radiation-transfer properties of the
specimen. (5)
DISCUSSION—
Typically, a reference detection system monitors the radiation incident on the specimen. This reference detection system serves to compensate for both
temporal and spectral variations in the flux incident upon the specimen, by normalization of readings from the instrument’s emission detection system.
blackbody,n—see the preferred term, full radiator.
A
bleached specimen, n—specimen whose absorptance has been decreased by chemical or radiant means. (1987) [TAPPI]
bleeding, n—the unintentional transfer of coloring matter from one medium to or through another.
bloom, n—the scattering of light in directions near the specular angle of reflection by a deposit on or exudation from a specimen.
blur, n—unsharpness (of an image). (2006)
DISCUSSION—
Blur may result from effects of motion, defocus, diffraction, or other factors.
blur, vt—to make (an image) less sharp. (2006)
body color, n—color produced by absorption and scattering of light by colorants within a colored material. (1988)
Bouguer’s law, n—the absorbance of a homogeneous sample is directly proportional to the thickness of the sample in the optical
A
path. (Also known as Lambert’s [thickness] law.) (1988) (E131)
B B
brightness, n—aspect of visual perception whereby an area appears to emit more or less light. (1995) [CIE] (F923)
brightness, n—of an object color, combination of lightness and saturation.
brightness, n—in the textile industry, perceived as saturated, vivid, deep, or clean.
DISCUSSION—
This usage may conflict with Definition 2 in the case of dark colors.
B B
brightness, n—(1) aspect of visual perception whereby an area appears to emit more or less light. (1995) [CIE] (F923)
(2) of an object color, combination of lightness and saturation.
(3) in the textile industry, perceived as saturated, vivid, deep, or clean.
DISCUSSION—
This usage may conflict with Definition 2 in the case of dark colors.
(4) of paper, reflectance of an infinitely thick specimen (reflectivity) measured for blue light with a centroid wavelength of
B
457 nm under specified spectral and geometric conditions of measurement. (1987) [TAPPI T 452]
(5) dyer’s, the color quality, combining lightness and saturation, that would be decreased by adding black, gray, or a
complementary color to a chromatic dye.
brightness, n—dyer’s, the color quality, combining lightness and saturation, that would be decreased by adding black, gray, or
a complementary color to a chromatic dye.
E284 − 22
bronzy color (or bronzing), n—a metallic coloration observed when viewing the light reflected at angles near the angle of
specular reflection, the color usually being quite different from that observed for other directions.
calibrate, v—to find and eliminate systematic errors of an instrument scale or method of measurement by use of material
standards and techniques traceable to an authorized national or international measurement system. (1994a)
DISCUSSION—
As defined here, calibration is normally carried out by an instrument manufacturer. See standardize, verify.
candela, cd,n—the SI unit of luminous intensity; the luminous intensity, in a given direction, of a source that emits
monochromatic radiation of frequency 540 × 10 hertz and that has a radiant intensity in that direction of (1/683) watt per
steradian.
DISCUSSION—
The lone frequency of 540 × 10 Hz mentioned in the definition has a wavelength of 555.016 nm in standard air, which for almost all purposes can
be taken to be 555 nm without affecting the accuracy of a real measurement. For sources at other frequencies (wavelengths), scale their spectral radiant
A
intensities by the spectral luminous efficiency function, V(λ). [CIE]
centroid wavelength, n—wavelength marking the center, in terms of area under a curve, of a function of wavelength weighted
by multiplication with a specified response function. (1988)
DISCUSSION—
In the case of (TAPPI) brightness (of paper) the response function is obtained by the use of a special blue tristimulus-colorimeter filter.
characterize, v—to specify the parameters or performance of an instrument or method of measurement. (1994)
DISCUSSION—
For example, in appearance measurement, the parameters might include the geometric and spectral nature of the illuminator and the receiver, and the
performance might be specified by measures of reliability, precision, and bias.
chatoyance, n—appearance characterized by a changeable luster or color, sometimes including a spatially-undulating narrow
white band or stripe.
chemical luminescence, n—luminescence resulting from a chemical reaction. (See also luminescence.)
chroma, n—(1) attribute of color used to indicate the degree of departure of the color from a neutral color of the same lightness.
See also Munsell chroma. (1989b)
chroma, n—(1) attribute of color used to indicate the degree of departure of the color from a neutral color of the same lightness.
See also Munsell chroma. (1989b)
2 2 1/2 2 2 1/2
(2) C*, (in the CIE 1976 L*, a*, b* or L*, u*, v* system) the quantity C* = (a* + b* ) or C* = (u* + v* ) . (1989b).
ab uv
(3) attribute of a visual perception, produced by an object color, that permits a judgment to be made of the amount of pure
chromatic color present, irrespective of the amount of achromatic color. (1995)
DISCUSSION—
See also saturation, Definition (2).
chroma, n—(3) attribute of a visual perception, produced by an object color, that permits a judgment to be made of the amount
of pure chromatic color present, irrespective of the amount of achromatic color. (1995)
DISCUSSION—
See also saturation, Definition (2).
chromatic, adj—perceived as having a hue; not white, gray, or black.
chromatic adaptation, n—changes in the visual system’s sensitivities due to changes in the spectral quality of illuminating and
viewing conditions. (1988)
E284 − 22
chromaticity, n—the color quality of a color stimulus definable by its chromaticity coordinates, or by its dominant (or
A
complementary) wavelength and its purity taken together. [CIE]
chromaticity coordinates, n—the ratio of each of the tristimulus values of any viewed light to the sum of the three. (1995)
DISCUSSION—
Chromaticity coordinates in the CIE 1931 system of color specification are designated by x, y, z and in the CIE 1964 supplementary system x , y ,
10 10
z .)
chromaticity diagram, n—a plane diagram in which points specified by chromaticity coordinates represent the chromaticities
B
of lights (color stimuli). (1995) [CIE]
chromaticness, n—(1) attribute of visual perception combining the hue and saturation. (1995)
chromaticness, n—(1) attribute of visual perception combining the hue and saturation. (1995)
(2) attribute of a visual perception according to which the color of an area appears to be more or less chromatic. (1995)
DISCUSSION—
B B B B
The term colorfulness is sometimes used as a synonym for Definition (2). [CIE, 1970] [CIE, 1987] [CIE, 1970] [CIE, 1987]
CIE, n—the abbreviation for the French title of the International Commission on Illumination, Commission Internationale de
l’Éclairage.
CIE color-rendering index, R,n—measure of the degree to which the computed chromaticity of a CIE test color sample
illuminated by a test illuminant conforms to that of the same sample illuminated by a reference illuminant. (1995)
DISCUSSION—
For eight CIE test-color samples, the results are CIE special color-rendering indices, R ,i = 1–8. The average of these is the CIE general color-rendering
i
C
index R . [CIE]
a
CIE primaries, n—the primary color stimuli used in the CIE system of colorimetry.
CIE spectral tristimulus values, n—tristimulus values or color-matching functions of the spectral components of an
equal-energy spectrum in the CIE (XYZ) system. (1990)
DISCUSSION—
The color matching functions are assigned the symbols x¯(λ), y¯(λ), z¯(λ) in the CIE 1931 colorimetric system and x¯ (λ), y¯ (λ), z¯ (λ) in the CIE
10 10 10
B
1964 supplementary colorimetric system. [CIE]
CIE 1931 (x,y) chromaticity diagram, n—chromaticity diagram for the CIE 1931 standard observer, in which the CIE 1931
chromaticity coordinates are plotted, with x as abscissa and y as ordinate. (1993)
CIE 1964 (x ,y ) chromaticity diagram,n—chromaticity diagram for the CIE 1964 supplementary standard observer, in which
10 10
the CIE 1964 chromaticity coordinates are plotted, with x as abscissa and y as ordinate. (1993)
10 10
CIE 1976 (u',v') or (u' ,v' ) chromaticity diagram,n—chromaticity diagram in which the CIE 1976 L* u* v* (CIELUV)
10 10
chromaticity coordinates are plotted, with u'(or u' ) as abscissa and v'(or v' ) as ordinate. (1993)
10 10
DISCUSSION—
These chromaticity diagrams should be used when diagrams more nearly equally visually spaced than the (x, y) or
(x , y ) diagrams are desired.
10 10
CIE 1931 standard colorimetric system, n—a system for determining the tristimulus values of any spectral power distribution
using the set of reference color stimuli X, Y, Z and the three CIE color-matching functions x¯(λ), y¯(λ), z¯(λ) adopted by the CIE
A
in 1931. (1987) [CIE]
E284 − 22
CIE standard illuminant A,n—colorimetric illuminant, representing the full radiator at 2855.6 K, defined by the CIE in terms
B
of a relative spectral power distribution. [CIE]
CIE standard illuminant B,n—colorimetric illuminant, representing direct sunlight with a correlated color temperature of 4874
K, defined by the CIE in terms of a relative spectral power distribution. Declared obsolete by the CIE in 1983. (1988)
CIE standard illuminant C,n—colorimetric illuminant, representing daylight with a correlated color temperature of 6774 K,
B
defined by the CIE in terms of a relative spectral power distribution. [CIE]
CIE standard illuminant D ,n—colorimetric illuminant, representing daylight with a correlated color temperature of 6504 K,
B
defined by the CIE in terms of a relative spectral power distribution. (1987) [CIE]
CIE 1931 standard observer, n—ideal colorimetric observer with color matching functions x¯(λ), y¯(λ), z¯(λ) corresponding to
B
a field of view subtending a 2° angle on the retina; commonly called the “2° standard observer.” (1988) [CIE]
B
CIE standard source A,n—a gas-filled tungsten-filament lamp operated at a correlated color temperature of 2855.6 K. [CIE]
CIE standard source B,n—standard source A combined with a specified liquid filter, to provide radiant flux with a correlated
color temperature of 4874 K. Declared obsolete by the CIE in 1983. (1988)
CIE standard source C,n—standard source A combined with a specified liquid filter, to provide radiant flux with a correlated
B
color temperature of 6774 K. (1988) [CIE]
CIE 1964 supplementary standard colorimetric system, n—a system for determining the tristimulus values of any spectral
power distribution using the set of reference color stimuli X , Y , Z , and the three CIE color-matching functions x¯ (λ),
10 10 10 10
A
y¯ (λ), z¯ (λ) adopted by the CIE in 1964. (1989) [CIE]
10 10
CIE 1964 supplementary standard observer, n—ideal colorimetric observer with color matching functions x¯ (λ), y¯ (λ),
10 10
z¯ (λ) corresponding to a field of view subtending a 10° angle on the retina; commonly called the “10° standard observer.”
B
(1988) [CIE]
CIE 1976 uniform-chromaticity-scale diagram, n—the uniform-chromaticity-scale diagram produced by plotting in
rectangular coordinates v'against u', quantities defined as follows:
u'5 4X/ X115Y13Z 5 4x/ 22x112y13 (2)
~ ! ~ !
v'5 9Y/~X115Y13Z! 5 9y/~22x112y13!
for the CIE 1931 standard colorimetric system, or v' against u' for the CIE 1964 supplementary standard colorimetric
10 10
A
system, in which case in the above formulae X , Y , Z are used instead of X, Y, Z and x , y instead of x, y. (1987) [CIE]
10 10 10 10 10
CIELAB color difference, n—color difference calculated by using the CIE 1976 L* a* b* opponent-color scales, based on
applying a cube-root transformation to CIE 1931 tristimulus values X, Y, Z or CIE 1964 tristimulus values X , Y , Z . (1988)
10 10 10
CIELUV color difference, n—color difference calculated by using the CIE 1976 L* u* v* opponent-color scales, based on a
linear transformation of CIE chromaticity coordinates x, y, or x , y and a cube-root transformation of Y or Y to L*, applied
10 10 10
to CIE 1931 tristimulus values X, Y, Z or CIE 1964 tristimulus values X , Y , Z . (1988)
10 10 10
circumferential, adj—descriptor for directional illuminating (or viewing) geometry in which the illuminator provides radiation
(or the receiver possesses responsivity) in many beams (or directions), normally distributed at uniform intervals throughout the
360° of azimuth of the measurement. The number and angular distribution of the beams (or directions) should be specified. (See
A
also annular.) (1990) (E1164)
E284 − 22
circumjacent field, n—the field surrounding the field of interest extending in all directions. (2012)
DISCUSSION—
The circumjacent field may be either a background or a surround. In art: A surround is an area that touches the object, or object field, on all sides and
will strongly affect its appearance. A background passes behind the object, or object field, and is further from it and so has a smaller effect on the
appearance of the object or object field. (2013)
clarity, n—the characteristic of a transparent body whereby distinct high-contrast images or high-contrast objects (separated by
some distance from the body) are observable through the body.
cmc (l:c) color difference,n—color difference calculated by use of the formula developed by the Colour Measurement
Committee of the Society of Dyers and Colourists of Great Britain. (1990)
DISCUSSION—
Based on the lightness, hue, chroma version of CIELAB, it incorporates chroma and hue-angle correction terms for improved visual spacing and
variable weighting factors for lightness (l) and chroma (c) relative to hue for improved correlation depending on type of judgment (acceptability,
perceptibility) and application (textiles, others).
coefficient of line retroreflection, R , n—of a reflecting stripe, the ratio of the coefficient of luminous intensity (R ) of a
M I
−1 −1 A
retroreflecting stripe to its length (l), expressed in candelas per lux per metre (cd·lx ·m ). R = (R /l). (1988) (E808)
M I
coefficient of luminous intensity R ,n—of a retroreflector, ratio of the luminous intensity (I) of the retroreflector in the direction
I
of observation to the illuminance (E ) at the retroreflector on a plane perpendicular to the direction of the incident light,
'
−1 A
expressed in candelas per lux (cd·lx ). R = (I/E ). (1988) (E808)
I '
coefficient of retroreflected luminance, R , n—ratio of the luminance, L, of a projected surface to the normal illuminance, E ,
L '
−2 −1
at the surface on a plane normal to the incident light, expressed in candelas per square metre per lux (cd·m ·lx ). R = (L/E ).
L '
B
(1988) (E808)
coefficient of retroreflection, R , n—of a plane reflecting surface, the ratio of the coefficient of luminous intensity (R ) of a plane
A I
−1 −2 A
retroreflecting surface to its area (A), expressed in candelas per lux per square metre (cd·lx ·m ). R = (R /A). (1988) (E808)
A I
collector, n—optical components, such as the cornea and lens of the eye, which guide radiant flux from a specimen being
observed or measured to a sensor.
DISCUSSION—
A collector and a sensor comprise a receiver.
color, n—(1) of an object, aspect of object appearance distinct from form, shape, size, position, or gloss that depends upon the
spectral composition of the incident light, the spectral reflectance or transmittance of the object, and the spectral response of the
observer, as well as the illuminating and viewing geometry. (1987)
color, n—(2) perceived, attribute of visual perception that can be described by color names such as white, gray, black, yellow,
brown, vivid red, deep reddish purple, or by combinations of such names.
DISCUSSION—
Perceived color depends greatly on the spectral power distribution of the color stimulus, but also on the size, shape, structure, and surround of the
A
stimulus area, the state of adaptation of the observer’s visual system, and the observer’s experience with similar observations. [TAPPI]
color, n—(1) of an object, aspect of object appearance distinct from form, shape, size, position, or gloss that depends upon the
spectral composition of the incident light, the spectral reflectance or transmittance of the object, and the spectral response of the
observer, as well as the illuminating and viewing geometry. (1987)
(2) perceived, attribute of visual perception that can be described by color names such as white, gray, black, yellow, brown,
vivid red, deep reddish purple, or by combinations of such names.
DISCUSSION—
Perceived color depends greatly on the spectral power distribution of the color stimulus, but also on the size, shape, structure, and surround of the
E284 − 22
A
stimulus area, the state of adaptation of the observer’s visual system, and the observer’s experience with similar observations. [TAPPI]
(3) colorimetric, characteristics of a color stimulus denoted by a colorimetric specification with three values, such as tristimulus
values.
DISCUSSION—
Tristimulus values are sometimes derived on a relative rather than an absolute basis. In this case they may need to be supplemented by the value of
a suitable absolute photometric quantity. The appearance of colors depends not only on their absolute tristimulus values, but also on the conditions
under which they are viewed, including the nature of the surround; however, colors having the same absolute tristimulus values appear the same in
A B
identical viewing conditions. Spectrally different color stimuli can have the same absolute tristimulus values. [TAPPI] [CIE]
color angle, n—in measurement of gonioapparent phenomena, half the angle between the illumination and detection axes of the
measurement geometry. (2008)
DISCUSSION—
The color of an interference pigment is determined by the angle of incidence of the light relative to the normal of the interference pigment flake. Flakes
in a coating have an angular distribution, and the interference effect will be exhibited in a given measurement geometry only by the flakes that are
oriented so that they behave as specular reflectors. Since the refractive index of the specimen is often unknown, color angle is defined here as if the
flakes were in air. Color angle provides a relative indication of the angle between the flake normal and the illuminator axis.
colorant, n—dye, pigment, or other agent used to impart a color to a material. (1988)
color atlas, n—a collection of color samples arranged according to a color order system. (1990)
color constancy, n—the general tendency of the colors of an object to remain constant when the color of the illumination is
changed.
color difference, n—(1) perceived, the magnitude and character of the difference between two colors described by such terms
as redder, bluer, lighter, darker, grayer, or cleaner.
color difference, n—(1) perceived, the magnitude and character of the difference between two colors described by such terms
as redder, bluer, lighter, darker, grayer, or cleaner.
(2) computed, the magnitude and direction of the difference between two psychophysical color stimuli and their components
computed from tristimulus values, or chromaticity coordinates and luminance factor, by means of a specified set of
color-difference equations.
color-difference units, n—units of size of the color differences calculated according to various equations. Such color differences
cannot be accurately converted between different equations by the use of average factors. (1988)
colorfulness,n—see chromaticness (2). (1991a)
color grading, n—the act of identifying a specimen by a color grade or color score, which is specific to the color and the material
graded.
colorimeter,n—see tristimulus colorimeter, visual colorimeter.
colorimetric purity, p , n—the fraction of spectrally pure light in an additive mixture with reference achromatic (white) light
c
to produce a color that matches that of the color stimulus considered. (As a reference achromatic light, the CIE recommends
B
an equal energy source for self-luminous bodies and illuminant D (daylight) for nonself-luminous bodies.) [CIE]
colorimetric spectrometer, n—spectrometer that is capable of producing spectral reflectance or transmittance data and
colorimetric data (such as tristimulus values and derived coordinates) derived from the spectral data. See spectrocolorimeter.
DISCUSSION—
Colorimetric spectrometers differ from UV-VIS analytical spectrometers by demanding more stability on the radiometric scale but allowing more
C
tolerance on the wavelength scale. (E2214)
colorimetry, n—the science of color measurement.
E284 − 22
color match, n—(1) condition existing when colors match within a specified or agreed tolerance. Sometimes called commercial
color match. (1988a)
DISCUSSION—
Compliance with tolerances can be determined instrumentally or visually. If the test for compliance is visual, physical color tolerance standards may
be used for reference.
(2) condition existing when colors are indistinguishable; a normal observer is usually implied. Sometimes called an exact
color match. (1988a).
color match, n—(2) condition existing when colors are indistinguishable; a normal observer is usually implied. Sometimes
called an exact color match. (1988a).
color matching, n—procedure for providing, by selection, formulation, adjustment, or other means, a trial color that is
indistinguishable from, or within specified tolerances of, a specified standard color under specified conditions. (1988a)
color-matching functions, n—the amounts, in any trichromatic system, of the three reference color stimuli needed to match by
an additive mixture monochromatic components of an equal energy spectrum.
DISCUSSION—
Symbols for these functions are lower case letters, each with a bar above and followed by the Greek letter λ in parentheses; the lower case letters
corresponding to the capital letter symbols for the r
...