ASTM D2244-09b
Standard Practice for Calculation of Color Tolerances and Color Differences from Instrumentally Measured Color Coordinates
- Standard No.
- ASTM D2244-09b
- Release Date
- 2009
- Published By
- American Society for Testing and Materials (ASTM)
- Status
- Replace By
- ASTM D2244-11
- Latest
- ASTM D2244-23
- Scope
The original CIE color scales based on tristimulus values X, Y, Z and chromaticity coordinates x, y are not uniform visually. 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. On the other hand, color differences obtained for the same specimens evaluated in different color-scale systems are not likely to be identical. 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. 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.
For uniformity of practice, the CIE recommended in 1976 the use of two color metrics. The CIELAB metric, with its associated color-difference equation, has found wide acceptance in the coatings, plastics, textiles and related industries. 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. 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 5.0 Δ E*ab units). The four more recently defined equations, documented here, are highly recommended for use with color-differences in the range of 0.0 to 5.0 ΔE*ab units.
Users of color tolerance equations have found that, in each system, summation of three, vector color-difference components into a single scalar value is very useful for determining whether a specimen color is within a specified tolerance from a standard. 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 possible to include information on the direction of a small color difference by listing the three instrumentally determined components of the color difference.
Selection of color tolerances based on instrumental values should be carefully correlated with a visual appraisal of the acceptability of differences in hue, lightness, and saturation obtained by using Practice D1729. 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 to within the experimental uncertainty of the visual judgments. That implies that the equations themselves misclassify a color difference with a frequency no greater than that of the most experienced visual color matcher.
While color difference equations and color tolerance equations are routinely applied to a wide range of illuminants, they have been derived or optimized, or both, for use under daylight illumination. Good correlation with the visual judgments may not be obtained when the calculations are made with other illuminants. Use of a tolerance equation for other than daylight conditions will require visual confirmation of the level of metamerism in accordance with ........
ASTM D2244-09b Referenced Document
- ASTM D1729 Standard Practice for Visual Appraisal of Colors and Color Differences of Diffusely-Illuminated Opaque Materials
- ASTM D4086 Standard Practice for Visual Evaluation of Metamerism
- ASTM E1164 Standard Practice for Obtaining Spectrophotometric Data for Object-Color Evaluation
- ASTM E284 Standard Terminology of Appearance
- ASTM E308 Standard Practice for Computing the Colors of Objects by Using the CIE System
- ASTM E805 Standard Practice for Identification of Instrumental Methods of Color or Color-Difference Measurement of Materials
ASTM D2244-09b history
- 2023 ASTM D2244-23 Standard Practice for Calculation of Color Tolerances and Color Differences from Instrumentally Measured Color Coordinates
- 2022 ASTM D2244-22 Standard Practice for Calculation of Color Tolerances and Color Differences from Instrumentally Measured Color Coordinates
- 2021 ASTM D2244-21 Standard Practice for Calculation of Color Tolerances and Color Differences from Instrumentally Measured Color Coordinates
- 2016 ASTM D2244-16 Standard Practice for Calculation of Color Tolerances and Color Differences from Instrumentally Measured Color Coordinates
- 2015 ASTM D2244-15a Standard Practice for Calculation of Color Tolerances and Color Differences from Instrumentally Measured Color Coordinates
- 2015 ASTM D2244-15e1 Standard Practice for Calculation of Color Tolerances and Color Differences from Instrumentally Measured Color Coordinates
- 2015 ASTM D2244-15 Standard Practice for Calculation of Color Tolerances and Color Differences from Instrumentally Measured Color Coordinates
- 2014 ASTM D2244-14 Standard Practice for Calculation of Color Tolerances and Color Differences from Instrumentally Measured Color Coordinates
- 2011 ASTM D2244-11 Standard Practice for Calculation of Color Tolerances and Color Differences from Instrumentally Measured Color Coordinates
- 2009 ASTM D2244-09b Standard Practice for Calculation of Color Tolerances and Color Differences from Instrumentally Measured Color Coordinates
- 2009 ASTM D2244-09a Standard Practice for Calculation of Color Tolerances and Color Differences from Instrumentally Measured Color Coordinates
- 2009 ASTM D2244-09 Standard Practice for Calculation of Color Tolerances and Color Differences from Instrumentally Measured Color Coordinates
- 2007 ASTM D2244-07e1 Standard Practice for Calculation of Color Tolerances and Color Differences from Instrumentally Measured Color Coordinates
- 2007 ASTM D2244-07 Standard Practice for Calculation of Color Tolerances and Color Differences from Instrumentally Measured Color Coordinates
- 2005 ASTM D2244-05 Standard Practice for Calculation of Color Tolerances and Color Differences from Instrumentally Measured Color Coordinates
- 2002 ASTM D2244-02e1 Standard Practice for Calculation of Color Tolerances and Color Differences from Instrumentally Measured Color Coordinates
- 2002 ASTM D2244-02 Standard Practice for Calculation of Color Tolerances and Color Differences from Instrumentally Measured Color Coordinates
- 1993 ASTM D2244-93(2000) Standard Test Method for Calculation of Color Differences From Instrumentally Measured Color Coordinates
