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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However, for control of color in production, it may be necessary to know not only the magnitude of the departure from standard but also the direction of this departure. It is intended to be used as a single-number shade-passing equation. Last previous edition approved in as D — Thus computed color differences are based only on the Euclidean distance in the DIN99 space.
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ASTM D – COLOR DETERMINATION
To avoid confusion, color differences among specimens or the associated tolerances should be compared only when they are obtained for the same color-scale system. The most common values are 2: Examples of Ka and Kb are tabulated in Table X1.
In the process, the researchers came to the conclusion that neither formula was truly optimum. There is no simple factor that can be used aatm convert accurately color differences or color tolerances in one system to difference or tolerance units in another system for all colors of specimens. By using the position of the arithmetic average color between the two specimens to compute the local distortions to CIELAB color space, the roles of the two specimens may be switched without ast, the magnitude of the computed colordifference, in full agreement with the visual assessments.
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Color Analysis – CIE94 (ASTM E1347 with ASTM D2244)
These scales do not provide a perceptually uniform color ast. 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.
Usually, the white object-color stimulus is given by the spectral radiant power of one of the CIE standard illuminants, for example, C, D65 or another phase of daylight, re? Current edition approved May 1, Due to copyright restrictions, we are not able to 2d244 copies of standards. The tristimulus values Xn, Yn, Zn de? This is convenient for certain textile sorting applications and for graphical quality control charting. Send us a request Wilton UK: Need help or have a question? While the CIELAB equation has not completely replaced the use of Hunter LH, aH, bH, this older scale is no longer recommended for other than legacy users, and is therefore included in an Appendix for historical purposes.
Hunter Lab and XYZ are standard three dimensional color spaces that allows a precise definition of the color of a test sample. The procedures for computing the DIN99 formula are: It was derived primarily from visual observations of automotive paints on steel panels. Standards can be obtained from appropriate standards authorities. Because of the many trigonometric functions and power functions involved in computing the color space parameters, all computations should be carried out in IEEE?
Inter-changing the reference and test specimens does not change either the perceived or predicted color differences.
ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentioned aatm this standard.
Visual color and spectrophotometer readings can also be affected by surface texture, molding parameters, processing method, and viewing light sources.
This standard is subject to revision at any time by the responsible technical committee and must be reviewed every? There is no simple factor that can be used to convert accurately color differences or color tolerances in one system to difference or tolerance units in another system for all colors of specimens.
Referenced Documents purchase separately The documents listed below are referenced within the subject standard but are not provided as part of the standard. The three tolerance equations given here have been tested extensively against such data for textiles and plastics and have been shown to agree with the visual evaluations astj within the experimental uncertainty of the visual judgments.
Each material and condition of use may require speci? Your comments ashm receive careful consideration at a meeting of the responsible technical committee, which you may attend.
ASTM D ColorTolerance_百度文库
Consequently, color differences are seldom if ever computed directly from differences in x, y, and Y. See Practice E Color analysis can be used to match adjacent parts molded from different materials, or to evaluate color change due to outdoor exposure.
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Where it is suspected that the specimens may be metameric, that is, possess different spectral curves though visually alike in color, Practice D should be used to verify instrumental results. Certification Formally confirming that your products and services meet all trusted external and internal standards. Color-difference units are computed, from these color-scale values, and approximate the perceived color differences between the reference and the test specimen.
This is contrary to what is observed.