ASTM E284-99a
(Terminology)Standard Terminology of Appearance
Standard Terminology of Appearance
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 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 (1-4)) 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.
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Designation: E 284 – 99a
Standard Terminology of
Appearance
This standard is issued under the fixed designation E 284; 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 (e) 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 E-12 on Appearance, the definitions in this terminology standard are taken to be
prescriptive in nature. Committee E-12 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 cal committees. Its use by committees other than Committee
E-12 on Appearance, and its citation in the standards of such
1.1 This terminology standard defines terms used in the
committees, is encouraged.
description of appearance, including but not limited to color,
2.2 In this terminology standard, definitions of terms used in
gloss, opacity, scattering, texture, and visibility of both mate-
other ASTM standards are indicated by placing the designation
rials (ordinary, fluorescent, retroreflective) and light sources
of that standard in parentheses at the end of the definition.
(including visual display units).
Definitions used by other organizations (see Refs (5–7)) are
1.2 It is the policy of ASTM Committee E-12 on Appear-
indicated similarly by placing in parentheses at the end of the
ance that this terminology standard include important terms
definition the acronym of the organization, occasionally with
and definitions explicit to the scope, whether or not the terms
the date of its terminology standard quoted. In either case, a
are currently used in an ASTM standard. Terms that are in
superscript letter may be used to indicate the degree of
common use and appear in common-language dictionaries (see
correspondence between the definition given herein and that in
Refs (1–4) ) are generally not included, except when the
the citation. Superscript A indicates that the two are identical;
dictionaries show multiple definitions and it seems desirable to
B that the given definition is a modification of that cited, with
indicate the definitions recommended for E 12 standards.
little difference in essential meaning; and C that the two differ
1.3 The usage of terms describing appearance varies con-
substantially.
siderably. In some cases, different usage of a term in different
2.3 A further parenthetical inclusion at the end of the
fields has been noted.
definition gives the revision, if after 1981, in which the
2. Significance and Use definition was added to this terminology standard or last
revised. An appendix at the end of this terminology standard
2.1 This terminology standard contains definitions of ap-
lists changes in it since its last previous revision published in
pearance terms applicable to the work of many ASTM techni-
the Annual Book of ASTM Standards.
2.4 Where appropriate, symbols or acronyms are listed for
These definitions are under the jurisdiction of ASTM Committee E-12 on Color
terms in this terminology standard. Since usage varies, these
and Appearance and is the direct responsibility of Subcommittee E12.01 on
Terminology. listings should be considered as recommendations, not as
Current edition approved June 10, 1999. Published August 1999. Originally
mandatory. If a different symbol or acronym is used in another
published as E 284 – 66 T. Last previous edition E 284 – 99.
ASTM standard, this should be indicated in that standard.
The boldface numbers in parentheses refer to a list of references at the end of
2.5 In the 1990 edition of this terminology standard, a great
text.
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
E 284
rated, the reported “accuracy” must be interpreted as a combination of
many terms were relocated to conform to the recommendation
these two elements. See bias, precision.
of the Form and Style for ASTM Standards, (Blue Book) that
listings be in spoken word order. In general, there are no
achromatic, adj—( 1) for primary light sources, the computed
crossreferences between the old and new listings, except where
chromaticity of the equal-energy spectrum. (1995)
a special function is served. An example of such a special
(2) for surface colors, the color of a whitish light, serving as
function is to list all terms relating to a given basic quantity, for
the illuminant, to which adaptation has taken place in the visual
example, all terms defining various sorts of angles.
system of the observer. (1995)
2.6 This terminology standard adopts the following usage of
(3) perceived as having no hue, that is, as white, gray, or
certain word endings. The ending “ion” denotes a process, as in
B
black. [CIE]
reflection; “ance” denotes a property of a specimen, as in
Adams color difference, n—color difference calculated by
reflectance; and“ ity” denotes a property of the kind of material
using the Adams-Nickerson opponent-color equations, based
of which the specimen is composed, as in reflectivity. Excep-
on applying the Munsell Value function to CIE 1931
tions exist, as in the common use of illumination and radiation
tristimulus values X, Y, Z. (1988)
to refer to quantities as well as processes.
additive color mixture, n—superposition or other nondestruc-
tive combination of lights of different perceived colors.
3. Terminology
(1995)
3.1 Definitions:
additive color stimulus mixture, n— method of simulation
AATCC blue wool lightfastness standards, n—standard that combines on the retina the actions of various color
dyed-wool samples of seven grades, each step in the series stimuli in such a manner that they cannot be perceived
A
representing a doubling of lightfastness. individually. (1995a) [CIE]
additive primaries, n— same as primary color stimuli.
DISCUSSION—Available from the American Association of Textile
ambient field, n—when an object or light source is viewed, the
Chemists and Colorists.
complete area beyond the surround from which light might
abridged spectrophotometry, n—the measurement of reflec-
reach the observer’s eyes and influence the object’s appear-
tance factor or transmittance factor in a number of wave-
ance. See surround.
length bands rather than as continuous functions of wave-
American Public Health Association (APHA) color, n—see
length.
platinum cobalt color scale.
angle, n—see aperture angle, aperture solid angle, azi-
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 muthal angle, entrance angle, observation angle, rotation
filters.
angle, specular angle.
angle of illumination, n—angle between the specimen normal
absorbance, A, n—logarithm to the base 10 of the reciprocal
and the illuminator axis. (1991b)
of the internal transmittance T . A 5 log (1/T ) 5 −log
I 10 I 10
B angle of incidence, n—the angle between a ray impinging on
T . (1990) (E 131)
I
a surface at a point and the perpendicular to the surface at
absorptance a, n—the ratio of the absorbed radiant or
A that point. In the description of a beam, the angle of
luminous flux to the incident flux. [CIE]
incidence of the ray at the center of the beam.
absorption, n—the transformation of radiant energy to a
angle of reflection, n—the angle between a ray reflected from
different form of energy by interaction with matter.
A
a surface at a point and the perpendicular to the surface at
[CIE]
that point.
absorption coefficient, a, n—measure of the absorption of
angle of view, n—angle between the normal to the surface of
radiant energy from an incident beam (P ) as it traverses an
o
−ab
the specimen and the axis of the receiver. (1988a)
absorbing medium according to Bouguer’s law, P 5 P e ,
o
angle, rotation, n— see rotation angle.
where b is the sample optical pathlength. (1988) (E 131)
angular subtense, n— visual, the angle subtended (by an
absorption tinting strength, n—relative change in the absorp-
object) at the first nodal point of the eye.
tion properties of a standard white material when a specified
annular, adj—descriptor for directional illuminating (or view-
amount of an absorbing colorant, black or chromatic, is
ing) geometry in which the illuminator provides radiation (or
added to it. (1988a)
the receiver possesses responsivity) that is distributed con-
DISCUSSION—See the Discussion to masstone.
tinuously and uniformly throughout the 360° of azimuth of
the measurement. (See also circumferential.) (1989)
absorptivity, a, n—the absorbance divided by the product of
(E 1164)
the concentration, c, of the substance and the sample optical
pathlength, b, a 5 A/bc. The units of b and c shall be aperture angle, 2k, n—angle subtended at a point on a
specimen by the maximum dimension of the illuminator or
specified. (1988) (E 131)
accuracy, n—the closeness of agreement between a test result receiver, within which the flux in a directional beam is
contained. (1990)
and an accepted reference value. (1993)
DISCUSSION—The qualitative term accuracy, when applied to a set of DISCUSSION—In optics, the symbol k is used for the half angle; hence
observed values, will be a combination of a random precision compo-
the recommended symbol here is 2k. (E 179)
nent and a systematic error or bias component. Since in routine use
random components and bias components cannot be completely sepa- aperture mode, n—color seen through an aperture which
E 284
prevents its association with a specific object or source. bidirectional, as in bidirectional optical measuring system.
aperture solid angle, v, n—solid angle subtended at a point (1991b)
bidirectional, adj— see bidirectional optical measuring sys-
on the specimen, defined by the sum of rays from the
illuminator or the sum of directions in which the receiver is tem. (1991)
sensitive to incoming radiation. (1990) (E 167) bidirectional optical measuring system, n—an optical sys-
aperture stop, n—the physical diameter that limits the size of tem for measuring the reflecting or transmitting properties of
specimens, wherein the illuminator and receiver each sub-
the cone of radiation that an optical system will accept from
A
an axial point on the object. (1988) [OSA] tend small angles at the specimen surface. (1988a)
blackbody, n— see the preferred term, full radiator.
appearance, n—( 1) the aspect of visual experience by which
things are recognized. (1990) bleached specimen, n—specimen whose absorptance has been
decreased by chemical or radiant means. (1987) [TAPPI]
(2) in psychophysical studies, visual perception in which the
spectral and geometric aspects of a visual stimulus are inte- bleeding, n—the unintentional transfer of coloring matter from
one medium to or through another.
grated with its illuminating and viewing environment. (1993)
(E 1499) bloom, n—the scattering of light in directions near the specular
angle of reflection by a deposit on or exudation from a
area reflector, n—reflector subtending a relatively large solid
angle at the observer’s eye, so that the observer can clearly specimen.
body color, n—color produced by absorption and scattering of
distinguish its size and shape. (1988)
light by colorants within a colored material. (1988)
artificial daylight, n—an artificial light that has a spectral
Bouguer’s law, n—the absorbance of a homogeneous sample
power distribution approximating that of a phase of natural
is directly proportional to the thickness of the sample in the
daylight. (1995)
optical path. (Also known as Lambert’s [thickness] law.)
aspecular, adj—away from the specular direction. (1995)
(1988) (E 131)
aspecular angle, n—viewing angle measured from the specu-
brightness, n—( 1) aspect of visual perception whereby an
lar direction, in the illuminator plane unless otherwise
B
area appears to emit more or less light. (1995) [CIE]
specified. (1995a)
(F 923)
DISCUSSION—Positive values of the aspecular angle are in the
(2) of an object color, combination of lightness and
direction toward the illuminator axis.
saturation.
(3) in the textile industry, perceived as saturated, vivid,
attributes of color—( 1) for the object mode of appearance,
hue, lightness, and saturation. In the Munsell system, Mun- deep, or clean.
sell Hue, Munsell Value, and Munsell Chroma.
DISCUSSION—This usage may conflict with Definition 2 in the case of
( 2) for the illuminant or aperture mode, hue, brightness,
dark colors.
and saturation.
(4) of paper, reflectance of an infinitely thick specimen
azimuthal angle, h, n—angle between the plane containing
(reflectivity) measured for blue light with a centroid wave-
the axis of the illuminator (or the path of illumination) and
length of 457 nm under specified spectral and geometric
the specimen normal and the plane containing the axis of the
conditions of measurement. (1987)
receiver (or the path of reception) and the specimen normal.
(5) dyer’s, the color quality, combining lightness and satu-
The origin and direction of measure of the angle should be
ration, that would be decreased by adding black, gray, or a
specified when required. (1990) (E 179)
complementary color to a chromatic dye. [TAPPI T 452]
azimuthal viewing, n—deprecated term; do not use. Replace
azimuthal by annular or circumferential. (1995a) bronzy color (or bronzing), n—a metallic coloration observed
basic color terms, n—a group of eleven color names found in when viewing the light reflected at angles near the angle of
anthropological surveys to be in wide use in fully developed specular reflection, the color usually being quite different
languages: white, black, red, green, yellow, blue, brown, from that observed for other d
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