Color Analysis – CIE94 (ASTM E with ASTM D). Color Analysis – Hunter (ASTM E & ASTM D). Scope: Hunter Lab and XYZ are standard . This standard is issued under the fixed designation D ; the number 1 This practice is under the jurisdiction of ASTM Committee E12 on Color and. ASTM D Standard Practice for Calculation of Color Tolerances and Color Differences from Instrumentally Measured Color Coordinates.
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ASTM D – COLOR DETERMINATION
All the k values default to 1 in the absence of speci? Use of a tolerance equation for other than daylight conditions will require visual con? For specimens that are matte, randomly rough, or mildly textured, values intermediate between 1: A previous revision added two new color tolerance equations and put two of the color difference equations from the version in an informative appendix for historical satm.
Current edition approved May 1, Its weighting functions are much simpler than those of the CMC equation. Each material and condition of use may require specific color tolerances because other appearance factors, for example, specimen proximity, gloss, and texturemay affect the correlation between the magnitude of a measured color difference and its commercial acceptability.
Color Analysis – CIE94 (ASTM E with ASTM D)
Good correlation with the visual judgments may not be obtained when the calculations are made with other illuminants. The CMC components and single number tolerances are computed as follows: Users of this standard are expressly advised that determination of the validity of any such patent rights, and the risk of infringement of such rights, are entirely their own responsibility.
Digital colorimetry allows more tolerance on the spectral scale and spectral bandwidth but demand much more stability in the radiometric scale. Nor is it possible or reasonable to plot groups of colors in terms of the modi? Each subsequent color scale based on CIE values has had weighting factors applied to provide some degree of uniformity so that color differences in various regions of color space will be more nearly comparable.
The CIELAB color-difference equation is also not recommended in this practice for use in describing small and moderate color differences differences with magnitude less than 5. There should not be a need to break the equation down into perceptual components—the CIELAB components of the model do that already.
The parameters kL, kC, kH, are the parametric factors that can be used to compensate for texture and other specimen presentation effects while kV is used to adjust the size of the tolerance volume for industrial bias.
The most common values are 2: This method of computing a metric hue d244 loses the information about the sign of the hue difference positive or negative and can be unstable for pairs of colors near the neutral axis. Good correlation with the visual judgments may not be obtained when the calculations are made with other illuminants.
Color-difference units are computed, from these color-scale values, and approximate the perceived color differences between the reference and the test specimen. Table 2 gives the mean color differences and their standard deviations for the groups of instruments considered While not obvious from this listing, all displayed angles are assumed to be given in degrees, including Du and thus must generally be converted into radians for d224 analysis astk digital computers.
Link to Active This link will always route to the current Active version of the asym. A color difference equation quanti? Auditing Consulting Sourcing Training.
The four more recently de? Visually, there is no change in asm magnitude of the difference between the specimens simply by switching roles. ASTM International takes no position respecting the validity of f2244 patent rights asserted in connection with any item mentioned in this standard. Standards can be obtained from appropriate standards authorities.
In the process, the researchers came to the conclusion that neither formula was truly optimum. ASTM D von It is intended to be used as a single-number shade-passing equation.
Your comments will receive careful consideration at a meeting of the responsible technical committee, which you may attend. Originally approved in The color dependent functions are de?
Thus the equation is highly optimized for pairwise comparison of a product standard to a production test specimen but not for statistical process control. Those conditions are given in D224 1. Your comments are invited either for revision of this standard or for additional standards and should be addressed to ASTM International Headquarters.