ASTM E1347-06(2011)
(Test Method)Standard Test Method for Color and Color-Difference Measurement by Tristimulus Colorimetry
Standard Test Method for Color and Color-Difference Measurement by Tristimulus Colorimetry
SIGNIFICANCE AND USE
The most direct and accessible methods for obtaining the color differences and color coordinates of object colors are by instrumental measurement using colorimeters or spectrophotometers with either hemispherical or bidirectional optical measuring systems. This test method provides procedures for such measurement by use of a colorimeter with either a bidirectional or a hemispherical optical measuring system.
This test method is suitable for measurement of color differences of nonmetameric, nonparameric pairs of object-color specimens, or color coordinates of most such specimens. A further limitation to the use of colorimeters having hemispherical geometry is the existence of a chromatic integrating-sphere error that prevents accurate measurement of color coordinates when the colorimeter is standardized by use of a white standard.
For the measurement of retroreflective specimens by this test method, the use of bidirectional geometry is recommended (See Guide E179 and Practice E805).
Note 3—To ensure inter-instrument agreement in the measurement of retroreflective specimens, significantly tighter tolerances than those given in Practice E1164 in the section on Influx and Efflux Conditions for 45°:Normal (45:0) and Normal:45° (0:45) Reflectance Factor are required for the instrument angles of illumination and viewing. Information on the required tolerances is being developed.
A requirement for the use of a colorimeter to obtain accurate color coordinates is that the combination of source, filter, and detector characteristics to duplicate accurately the combined characteristics of a CIE standard illuminant and observer. When this requirement is not met, this test method requires the use of local standards for improving accuracy in the measurement of color coordinates (see also 4.2). For the measurement of small color differences between nonmetameric, nonparameric specimens, accuracy in absolute color coordinates is less important and standardization of the colo...
SCOPE
1.1 This test method covers the instrumental measurement of specimens resulting in color coordinates and color difference values by using a tristimulus colorimeter, also known as a tristimulus filter colorimeter or a color-difference meter.
1.2 Provision is made in this test method for the measurement of color coordinates and color differences by reflected or transmitted light using either a hemispherical optical measuring system, such as an integrating sphere, or a bidirectional optical measuring system, such as annular, circumferential, or uniplanar 45:0 and 0:45 geometry.
1.3 Because of the limited absolute accuracy of tristimulus colorimeters, this test method specifies that, when color coordinates are required, the instrument be standardized by use of a standard having similar spectral (color) and geometric characteristics to those of the specimen. This standard is also known as a product standard. The use of a product standard of suitable stability is highly desirable.
1.4 Because tristimulus colorimeters do not provide any information about the reflectance or transmittance curves of the specimens, they cannot be used to gain any information about metamerism or paramerism.
1.5 Because of the inability of tristimulus (filter) colorimeters to detect metamerism or paramerism of specimens, this test method specifies that, when color differences are required, the two specimens must have similar spectral (color) and geometric characteristics. In this case, the instrument may be standardized for reflectance measurement by use of a white reflectance standard or, for transmittance measurement, with no specimen or standard at the specimen position.
1.6 This test method is generally suitable for any non-fluorescent, planar, object-color specimens of all gloss levels. Users must determine whether an instrument complying with this method yields results that are useful to evaluate and characterize retroreflective speci...
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Designation: E1347 − 06 (Reapproved2011)
Standard Test Method for
Color and Color-Difference Measurement by Tristimulus
Colorimetry
This standard is issued under the fixed designation E1347; 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.
1. Scope this method yields results that are useful to evaluate and
characterize retroreflective specimens, or specimens having
1.1 This test method covers the instrumental measurement
optical structures.
ofspecimensresultingincolorcoordinatesandcolordifference
values by using a tristimulus colorimeter, also known as a
1.7 This test method does not apply to the use of a
tristimulus filter colorimeter or a color-difference meter.
spectrocolorimeter, which is a spectrometer that provides
colorimetric data, but not the underlying spectral data. Mea-
1.2 Provision is made in this test method for the measure-
surement by using a spectrocolorimeter is covered in Practice
ment of color coordinates and color differences by reflected or
E1164 and methods on color measurement by spectrophotom-
transmitted light using either a hemispherical optical measur-
etry.
ing system, such as an integrating sphere, or a bidirectional
optical measuring system, such as annular, circumferential, or
1.8 This standard does not purport to address all of the
uniplanar 45:0 and 0:45 geometry.
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro-
1.3 Because of the limited absolute accuracy of tristimulus
priate safety and health practices and determine the applica-
colorimeters, this test method specifies that, when color coor-
bility of regulatory limitations prior to use.
dinates are required, the instrument be standardized by use of
a standard having similar spectral (color) and geometric
2. Referenced Documents
characteristics to those of the specimen. This standard is also
known as a product standard. The use of a product standard of
2.1 ASTM Standards:
suitable stability is highly desirable.
D2244 Practice for Calculation of Color Tolerances and
Color Differences from Instrumentally Measured Color
1.4 Because tristimulus colorimeters do not provide any
Coordinates
informationaboutthereflectanceortransmittancecurvesofthe
E179 Guide for Selection of Geometric Conditions for
specimens, they cannot be used to gain any information about
Measurement of Reflection and Transmission Properties
metamerism or paramerism.
of Materials
1.5 Because of the inability of tristimulus (filter) colorim-
E284 Terminology of Appearance
eters to detect metamerism or paramerism of specimens, this
E805 Practice for Identification of Instrumental Methods of
test method specifies that, when color differences are required,
Color or Color-Difference Measurement of Materials
the two specimens must have similar spectral (color) and
E1164 PracticeforObtainingSpectrometricDataforObject-
geometric characteristics. In this case, the instrument may be
Color Evaluation
standardized for reflectance measurement by use of a white
E1345 Practice for Reducing the Effect of Variability of
reflectance standard or, for transmittance measurement, with
Color Measurement by Use of Multiple Measurements
no specimen or standard at the specimen position.
1.6 This test method is generally suitable for any non-
3. Terminology
fluorescent, planar, object-color specimens of all gloss levels.
3.1 Definitions:
Users must determine whether an instrument complying with
3.1.1 The definitions contained in Guide E179 and Termi-
nology E284 are applicable to this test method.
This test method is under the jurisdiction of ASTM Committee E12 on Color
and Appearance and is the direct responsibility of Subcommittee E12.02 on
Spectrophotometry and Colorimetry. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Nov. 1, 2011. Published November 2011. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 1990. Last previous edition approved in 2006 as E1347 – 06. DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/E1347-06R11. the ASTM website.
Copyright ©ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA19428-2959. United States
E1347 − 06 (2011)
4. Summary of Test Method with colorimeters in which there is good conformance of the
colorimeter readings to CIE tristimulus values, as determined
4.1 This test method provides procedures for measuring
by measurement of suitable verification standards (see Practice
object-color specimens in either transmission or reflection with
E1164).Withinstrumentsnotmeetingthisrequirement,theuse
atristimuluscolorimeter(hereafterreferredtoasacolorimeter)
of local standards is recommended, but only when the signal
by use of the following geometric conditions and standardiza-
level (see Note 2) from the use of each colorimeter filter is
tion procedures:
adequately high.
4.1.1 Color differences by reflected light of nonmetameric,
nonparameric pairs of opaque or translucent specimens by use
NOTE 1—Of necessity, the above requirements are in part subjective, as
the methods for verifying conformance to the requirements may not be
ofeitherhemisphericalgeometry,withanintegratingsphere,or
available to the average user. Each user must decide whether the
bidirectional geometry, such as annular, circumferential, or
standardization procedure selected results in a loss of accuracy in the
uniplanar 45:0 or 0:45 geometry. The colorimeter may be
measurements that is negligibly small for the purpose for which data are
standardized by use of a white reflectance standard.
obtained.
4.1.2 Color differences by transmitted light of
NOTE 2—The adequacy of the signal level can be determined by
measuring the short-term repeatability without replacement, and ascer-
nonmetameric, nonparameric pairs of transparent or translu-
taining that the variation in the answer represents less than 30 % of the
cent specimens by use of hemispherical geometry. The colo-
desired or allowable variation.
rimeter may be standardized by use of a white standard at the
4.2.2 When color differences are to be measured, only
reflection port of the integrating sphere with no specimen in
relative measured values are required for the two members of
place. When translucent specimens are measured, they should
the color-difference pair, and standardization by use of either a
be placed flush against the transmission port of the sphere, and
white standard or a local standard is satisfactory. In those cases
the white standard should, for maximum accuracy, have the
where a computer program is being used to predict color
samereflectanceandchemicalcompositionasthatofthelining
tolerances, accuracy of the absolute values of the product
of the integrating sphere.
standard color coordinates may become more important (see
4.1.3 Color coordinates by reflected light of opaque or
4.2.1).
translucent specimens by use of either bidirectional or hemi-
spherical geometry. The colorimeter may be standardized by
4.3 Procedures for selecting specimens suitable for preci-
use of a standard having spectral (color) and geometric
sion measurement are included in this test method.
characteristics similar to those of the specimens. Such
4.4 Most modern colorimeters compute the color coordi-
standards, often called hitching-post standards, are hereafter
natesofthespecimenduringthemeasurement.Whenthisisthe
referred to as local standards.
case, the user of this test method must designate the color
4.1.4 Color coordinates by transmitted light of transparent
system to be used in the computation (see Practice D2244).
or translucent specimens by use of hemispherical geometry.
The colorimeter may be standardized by use of a local
5. Significance and Use
standard.
5.1 The most direct and accessible methods for obtaining
4.1.5 This test method is not appropriate for fluorescent
the color differences and color coordinates of object colors are
specimens.
by instrumental measurement using colorimeters or spectro-
4.1.6 For the measurement of the daytime color of retrore-
photometers with either hemispherical or bidirectional optical
flective specimens, the 45:0 or 0:45 conditions are normally
measuring systems. This test method provides procedures for
required. Some modern, high brightness, retroreflective sheet-
such measurement by use of a colorimeter with either a
ing has been shown to exhibit geometric artifacts if the cone
bidirectional or a hemispherical optical measuring system.
angles are too narrow. In these cases, it may be more
appropriate to use larger cone angles, with appropriate toler-
5.2 This test method is suitable for measurement of color
ances.
differences of nonmetameric, nonparameric pairs of object-
4.1.7 When the specimens exhibit directionality, and a
color specimens, or color coordinates of most such specimens.
colorimeter with uniplanar bidirectional geometry is used,
A further limitation to the use of colorimeters having hemi-
information on directionality may be obtained by measuring
spherical geometry is the existence of a chromatic integrating-
the specimens at more than one rotation angle, typically at two
sphere error that prevents accurate measurement of color
angles 90° apart. When such information is not required, these
coordinates when the colorimeter is standardized by use of a
measurements may be averaged, or a colorimeter with annular
white standard.
or circumferential bidirectional geometry may be used.
5.3 For the measurement of retroreflective specimens by
4.2 This test method includes two different procedures for
this test method, the use of bidirectional geometry is recom-
standardizing the colorimeter. The first procedure utilizes a
mended (See Guide E179 and Practice E805).
white standard of known reflectance factor; the second proce-
NOTE 3—To ensure inter-instrument agreement in the measurement of
dure utilizes a local standard.
retroreflective specimens, significantly tighter tolerances than those given
4.2.1 When absolute values of color coordinates are to be
in Practice E1164 in the section on Influx and Efflux Conditions for
determined, the use of a white standard is recommended only
3 4
Hunter, R. S., “Photoelectric Tristimulus Colorimetry with Three Filters,” Hoffman, K., “Chromatic Integrating-Sphere Error in Tristimulus
Journal, Optical Society of America, Vol 32, 1942, pp. 509–558. Colorimeters,” Journal of Color and Appearance, Vol 1, No. 2, 1971, pp. 16–21.
E1347 − 06 (2011)
45°:Normal (45:0) and Normal:45° (0:45) Reflectance Factor are required
8.1.2 Verify the accuracy of the standardization and the
for the instrument angles of illumination and viewing. Information on the
instrument performance by measuring a series of verification
required tolerances is being developed.
standards (recommended).
5.4 A requirement for the use of a colorimeter to obtain
8.2 Standardization for Measurement of Color Coordinates:
accurate color coordinates is that the combination of source,
filter, and detector characteristics to duplicate accurately the NOTE 4—If the verification tests of 8.2.2 are not to be carried out, omit
8.2.1 and 8.2.2 and proceed to 8.2.3.
combined characteristics of a CIE standard illuminant and
observer. When this requirement is not met, this test method
8.2.1 Standardize the colorimeter by use of the white
requires the use of local standards for improving accuracy in
standard (mandatory) and the zero-reading standard (if
the measurement of color coordinates (see also 4.2). For the
required), following the manufacturer’s instructions.
measurement of small color differences between
8.2.2 Verify the accuracy of the standardization and the
nonmetameric, nonparameric specimens, accuracy in absolute
instrument performance by measuring a series of verification
color coordinates is less important and standardization of the
standards (recommended).
colorimeterbyuseofawhitestandardissatisfactory.However,
8.2.3 Standardize the colorimeter by use of the appropriate
accurate color-difference measurement requires that specimen
local standard for the specimens to be measured (mandatory)
pairs have similar spectral and geometric characteristics.
and the zero-reading standard (if required), following the
manufacturer’s instructions.
6. Apparatus
9. Procedure
6.1 Colorimeter, designed for the measurement of object-
color specimens. Use hemispherical geometry for reflection or
9.1 When required, select the color scales to be used in the
transmission measurements or bidirectional geometry for re-
computation of color coordinates or color differences.
flection measurements.
9.2 Handle the specimen carefully; avoid touching the area
6.2 Standardization Plaques, supplied by the manufacturer.
to be measured. When necessary, clean the specimen by an
6.2.1 White Reflecting Tile or Standard (Mandatory)—(If
agreed procedure.
the colorimeter has hemispherical geometry, a standard of
9.3 Whenhemisphericalgeometryisused,makethefollow-
hemispherical reflectance factor is required; if bidirectional
ing selections:
geometry, a standard of bidirectional reflectance factor is
9.3.1 For the measurement of reflecting specimens, select
required.)
inclusion or exclusion of the specular component of reflection
6.2.2 Local Standardization Plaques (Recommended), hav-
as desired (see Guide E179 and Practice E805).
ing spectral (color) and geometric characteristics similar to
9.3.1.1 Ifthespecimenistranslucent,backitwithastandard
those of specimens to be measured, as required for the
backing material during the measurement.
measurement of color coordinates.
6.2.3 Light Trap (Hemispherical) or Polished Black Glass 9.3.2 For the measurement of fully transparent specimens
by transmission, place the specimen in the transmission com-
(Bidirectional) Standards (Recommended; mandatory if so
indicated by the manufacturer),forsettingorverifyingthezero partment of the colorimeter.
reading of the colorimeter. 9.3.2.1 If total luminous quantities are desired, place the
specimen flush against the transmission measurement port of
6.3 Verification Standards (Recommended), supplied by the
the integrating sphere.
manufacturer or obtained separately.
9.3.2.2 If regular luminous quantities are desired, place the
6.4 Standard Backing Material(s) (Recommended), for
specimen as far away from the sphere port as possible.
backing translucent specimens during measurement.
9.3.3 For the measurement of translucent specimens,
...
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