ASTM D4086-92a(2003)

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Designation:D4086–92a(Reapproved2003)
Standard Practice for
Visual Evaluation of Metamerism
This standard is issued under the fixed designation D 4086; 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
Because perceived color involves the spectral characteristics of source, object, and eye, different
combinations of spectral characteristics can evoke the same color sensation. For this reason,
metamerism has been described as “invisible spectral differences.”
Apairofspecimensissaidtobemetamericwhenthespecimensmatchunderonesetofilluminating
and viewing conditions and do not match under another set. For this condition to exist, there must be
differences in spectral character of specimens and sources or specimens and observers. There may be
more than one condition under which the specimens match, as well as more than one for which they
are a mismatch. Similarly, two specimens may be a near-match under one set of conditions, and under
another set the direction and magnitude of the color difference may change.
1. Scope D 2616 Test Method for Evaluation of Visual Color Differ-
ence With a Gray Scale
1.1 This practice describes visual methods for detecting
E 284 Terminology of Appearance
metamerism and for estimating the magnitude of a metameric
color difference.
3. Terminology
1.2 The practice is limited to the consideration of illuminant
3.1 Definitions of appearance terms used in this practice
metamerism and observer metamerism. It is not designed to
may be found in Terminology E 284.
cover so-called geometric metamerism, in which members of
3.2 Definitions:
specimen pairs change relative appearance as the angles of
3.2.1 metamerism, n—property of two specimens that
illumination and viewing are changed, for example, because
match under a specified illuminator and to a specified observer
they incorporate flake metal or pearlescent colorants.
and whose spectral reflectances or transmittances differ in the
1.3 This practice does not provide for the computation of
visible wavelengths.
indices of metamerism based upon instrumental measurement
3.2.1.1 Discussion—As a consequence of the required dif-
of spectral characteristics.
ference, the two specimens may not match under a different
1.4 This standard does not purport to address all of the
illuminator or to a different observer. Similar considerations
safety concerns, if any, associated with its use. It is the
apply to two lights matching to a specified observer but not to
responsibility of the user of this standard to establish appro-
other observers. (E 284)
priate safety and health practices and determine the applica-
3.2.2 paramerism, n—phenomenon in which specimens
bility of regulatory limitations prior to use.
having different spectrophotometric curves produce approxi-
2. Referenced Documents mately the same color sensation under the same illuminating
and viewing conditions. (E 284)
2.1 ASTM Standards:
4. Significance and Use
4.1 Metameric color matches result from the use of different
This practice is under the jurisdiction of ASTM Committee E12 on Color and
colorants (pigments, dyes, and the like) in achieving the same
Appearance and is the direct responsibility of Subcommittee E12.11 on Visual
color match. Usually, the purchaser requires that the color
Methods.
match be nonmetameric; this practice permits this requirement
Current edition approved Dec. 1, 2003. Published December 2003. Originally
e1
approvedin1982.Lastpreviouseditionapprovedin1992asD 4086 – 92a (1997) .
to be quickly tested in both field and laboratory. Where
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
nonmetameric matches are not possible or practicable, for cost
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
or other reasons, some limitation of metamerism may be
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. required. The procedures for estimating the magnitude of
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D4086–92a (2003)
metamerism described in this practice provide methods for D 2616, Section 5.1 that, the total color difference can be so
assessing the effectiveness of such limitation. evaluated in terms of an equivalent lightness difference.
Observers can be expected to reproduce such evaluations
5. Test Specimens
within a half-step on the gray scale.
5.1 This practice does not cover the preparation of test
NOTE 1—Visual Evaluation of Spectral Reflectance Curves—When
specimens. The method shall be agr
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