ASTM D2616-12
(Test Method)Standard Test Method for Evaluation of Visual Color Difference With a Gray Scale
Standard Test Method for Evaluation of Visual Color Difference With a Gray Scale
SIGNIFICANCE AND USE
The total perceived color difference between two non-self luminous specimens is compared as an equivalent lightness difference between two neutral gray specimens on a gray scale. A fundamental assumption is made that the total color difference can be so evaluated in terms of an equivalent lightness difference. Only the total color differences, that is, a summation of the differences in hue, lightness, and chroma between two specimens is evaluated; this test method is not applicable to the separate precise evaluation of the hue, lightness, and chroma components of color difference.
The total color difference determined by this test method depends on the degree of uniformity of the specimens and on the sharpness of the dividing line between them. The color difference between specimens having rough or mottled surfaces appears smaller than it would if the specimens had smooth and uniform surfaces. Thus the equivalent CIELAB lightness difference determined for non-uniform specimens will be smaller than for uniform specimens. Likewise, specimens whose dividing line is not sharp will appear to have smaller color differences than those with sharp dividing lines, and for this reason, the equivalent visually observed CIELAB lightness differences will be smaller than the color differences obtained from instrumental measurements.
A physically sharp border between colors differing slightly in the yellow-blue direction in color space appears diffuse. The perceived color difference is noticeably increased by a hairline black separation. This technique imposes a more rigorous test of such small differences.
In the CIELAB system, a unit of color difference is intended to represent the same visual difference in each of the three attributes; lightness, hue and chroma or alternatively lightness, redness-greeness, yellowness-blueness. It is valid to express color differences that are not simply lightness differences by comparison to a lightness-difference scale.
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SCOPE
1.1 This test method describes a painted gray scale and the procedure to be used in the visual evaluation of color differences of non-self luminous materials by comparison to this scale.
1.2 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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Designation: D2616 − 12
Standard Test Method for
1
Evaluation of Visual Color Difference With a Gray Scale
This standard is issued under the fixed designation D2616; 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
This test method was developed to provide a precise procedure for visually evaluating color
difference of non-self luminous specimens. It was patterned after a method standardized by the
2
American Association of Textile Chemists and Colorists (AATCC) designed to evaluate “change in
color” and this antecedent was reflected in the original title.
This test method provides for evaluation of small to moderate color differences (less than 15
CIELAB (International Commission on Illumination) color difference units) by comparing test
specimens to a series of paired gray color chips having progressively larger lightness differences.
Color difference is rated according to which of nine gray pairs of differences is visually closest to the
test pair, or by interpolation between gray-pair differences.
1. Scope 2.2 AATCC Procedures:
AATCC Evaluation Procedure 1 Gray Scale for Color
1.1 This test method describes a painted gray scale and the
2
Change
procedure to be used in the visual evaluation of color differ-
ences of non-self luminous materials by comparison to this
3. Terminology
scale.
3.1 Definitions:
1.2 This standard does not purport to address all of the
3.1.1 Definitions of appearance terms in Terminology E284
safety concerns, if any, associated with its use. It is the
are applicable to this test method.
responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica-
4. Summary of Test Method
bility of regulatory limitations prior to use.
4.1 The gray scale consists of nine pairs of neutral gray
2. Referenced Documents
color standards of which Reference Pair 5 is two examples of
3
thesamegray.Oneelementcommontoeachpairisthegrayof
2.1 ASTM Standards:
Reference Pair 5; the other element, being progressively
E284Terminology of Appearance
lighter, provides a succession of lightness differences. Total
E1729Practice for Field Collection of Dried Paint Samples
color differences between non-self luminous specimens are
for Subsequent Lead Determination
expressed as either fractional, linear scale value between 1 and
E1499Guide for Selection, Evaluation, and Training of
5 by comparison with the paired differences of the gray scale,
Observers
which are predominantly lightness differences.
NOTE 1—The gray specimen common to each pair is specified to have
1
CIE 1976 metric lightness, L*=41.2 (+ 0.6, − 0.60).
This test method is under the jurisdiction of ASTM Committee E12 on Color
andAppearance and is the direct responsibility of Subcommittee E12.11 on Visual
Methods.
5. Significance and Use
Current edition approved July 1, 2012. Published September 2012. Originally
approved in 1967. Last previous edition approved in 2003 as D2616 – 96 (2003)
5.1 The total perceived color difference between two non-
which was withdrawn April 2012 and reinstated in July 2012. DOI: 10.1520/
selfluminousspecimensiscomparedasanequivalentlightness
D2616–12.
differencebetweentwoneutralgrayspecimensonagrayscale.
2
Technical Manual of the American Association of Textile Chemists and
A fundamental assumption is made that the total color differ-
Colorists, P.O. Box 12215, Research Triangle Park, NC 27709, Vol 86, 2011, pp.
365–366.
ence can be so evaluated in terms of an equivalent lightness
3
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
difference.Onlythetotalcolordifferences,thatis,asummation
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
of the differences in hue, lightness, and chroma between two
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. specimensisevaluated;thistestmethodisnotapplicabletothe
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1
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D2616 − 12
separate precise evaluation of the hue, lightness, and chroma 6.2 Gray Masks—Light gray masks with rectangular open-
components of color difference. ings shall be used to ensure comparison of equal areas of
specimen and reference pairs. Masks are included with each
AATCC gray-scale chart.
TABLE 1 Gray Scale Characteristics
6.3 Color Matching Light Booth—See Practice E1729 for a
CIELAB (∆E*)
AATCC Step
Designations description of an appropriate color-matching light booth for
Color
...
This document is not anASTM standard and is intended only to provide the user of anASTM 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:D2616–96(Reapproved2003) Designation:D2616–12
Standard Test Method for
1
Evaluation of Visual Color Difference With a Gray Scale
This standard is issued under the fixed designation D2616; 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
This test method was developed to provide a precise procedure for visually evaluating color
difference of non-self luminous specimens. It was patterned after a method standardized by the
2
American Association of Textile Chemists and Colorists (AATCC) designed to evaluate “change in
color” and this antecedent was reflected in the original title.
This test method provides for evaluation of small to moderate color differences (less than 15
CIELAB (International Commission on Illumination) color difference units) by comparing test
specimens to a series of paired gray color chips having progressively larger lightness differences.
Color difference is rated according to which of nine gray pairs of differences is visually closest to the
test pair, or by interpolation between gray-pair differences.
The gray-scale pairs are specified in terms of decimal differences in CIELAB color space. This
change together with two continuous, decimal numerical scale equations modeling the original scale
comprisethemajordifferencesbetweenthepreviouseditionandthisrevision.Thechangesweremade
to provide an ASTM test method that parallels closely the AATCC method.
1. Scope
1.1 This test method describes a painted gray scale and the procedure to be used in the visual evaluation of color differences
of non-self luminous materials by comparison to this scale.
1.2 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory
limitations prior to use.
2. Referenced Documents
3
2.1 ASTM Standards:
E284 Terminology of Appearance
DE1729Practice for VisualAppraisal of Colors and Color Differences of Diffusely-Illuminated Opaque Materials Practice for
Field Collection of Dried Paint Samples for Subsequent Lead Determination
E1499 Guide for Selection, Evaluation, and Training of Observers
2.2 AATCC Procedures:
2
AATCC Evaluation Procedure 1,Gray1 Gray Scale for Color Change
3. Terminology
3.1 Definitions:
3.1.1 Definitions of appearance terms in Terminology E284 are applicable to this test method.
4. Summary of Test Method
4.1 The gray scale consists of nine pairs of neutral gray color standards of which Reference Pair 5 is two examples of the same
1
ThistestmethodisunderthejurisdictionofASTMCommitteeE12onColorandAppearanceandisthedirectresponsibilityofSubcommitteeE12.11onVisualMethods.
Current edition approved Dec. 1, 2003. Published December 2003. Originally approved in 1967. Last previous edition approved in 1996 as D2616–96. DOI:
10.1520/D2616-96R03.
Current edition approved July 1, 2012. Published September 2012. Originally approved in 1967. Last previous edition approved in 2003 as D2616 – 96 (2003) which was
withdrawn April 2012 and reinstated in July 2012. DOI: 10.1520/D2616–12.
2
Technical Manual of the American Association of Textile Chemists and Colorists, P.O. Box 12215, Research Triangle Park, NC 27709, Vol 68, 1993,86, 2011, pp.
348–349.365–366.
3
ForreferencedASTMstandards,visittheASTMwebsite,www.astm.org,orcontactASTMCustomerServiceatservice@astm.org.For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
1
---------------------- Page: 1 ----------------------
D2616–12
gray. One element common to each pair is the gray of Reference Pair 5; the other element, being progressively lighter, provides
a succession of lightness differences. Total color differences between non-self luminous specimens are expressed as either
fractional, linear scale value between 1 and 5 or as equivalent CIELAB color differences (DE* ) by comparison with the paired
ab
differences of the gray scale, which are predominantly lightness differences.
NOTE 1—The gray specimen common to each pair is specified to have CIE 1976 metric lightness, L*=41.2(+0.6,−0.0).
...
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