ASTM D2244 DOWNLOAD

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ASTM D is a standard test method for calculating color differences from We also invite you to download our PDF on the true color measurement: What is . 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. Home; ASTM D standard by ASTM International, 07/01/ . View all Printed Edition + PDF;; Immediate download; $; Add to Cart.


Astm D2244 Download

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ASTM D ColorTolerance - 巴巴客 computerescue.info 免费下载标准 Free download from computerescue.info Designat. Downloaded/printed by. GAMESA INNOVATION & TECHNOLOGY pursuant to License Agreement. No further reproductions authorized. D 11 3. ASTM D Standard Practice for Calculation of Color Tolerances and Color Differences from. Instrumentally Measured Color Coordinates describes the.

Published May Originally approved in Last previous edition approved in as D — Terminology 3.

Additionally, the colorimetric spectrometer may also be able to report the underlying spectral data from which the colorimetric data were derived. Today, while instruments intended for use in color measurements share many common components, UV-VIS analytical spectrophotometers are designed to optimize their use in chemometric quantitative analysis, which requires very precise spectral position and very narrow bandpass and moderate baseline stability.

Colorimetric spectrometers are designed to optimize their use as digital simulations of the visual colorimeter or as the source of spectral and colorimetric information for computer-assisted color matching systems. Digital colorimetry allows more tolerance on the spectral scale and spectral bandwidth but demand much more stability in the radiometric scale. A color difference equation quanti? Inter-changing the reference and test specimens does not change either the perceived or predicted color differences.

Summary of Practice 4. Color-difference units are computed, from these color-scale values, and approximate the perceived color differences between the reference and the test specimen. Each subsequent color scale based on CIE values has 2 6.

Color Guide

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.

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.

The four more recently de? 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.

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.

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 con?

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These scales do not provide a perceptually uniform color space. Consequently, color differences are seldom if ever computed directly from differences in x, y, and Y.

The tristimulus values Xn, Yn, Zn de? 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? Under these conditions, Xn, Yn, Zn are the tristimulus values of the standard illuminant with Yn equal to This method of computing a metric hue difference 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.

It is intended to be used as a single-number shade-passing equation. There should not be a need to break the equation down into perceptual components—the CIELAB components of the model do that already.

Standard Practice for

The most common values are for textiles and plastics that are molded to simulate a woven material, implying that lightness differences carry half the importance of chroma and hue differences The values , often assumed to represent a just perceptible difference, should be applied to materials that require very critical tolerances or have glossy surfaces. For specimens that are matte, randomly rough, or mildly textured, values intermediate between and can be used, with the value 1.

The color dependent functions are de? It was derived primarily from visual observations of automotive paints on steel panels. Its weighting functions are much simpler than those of the CMC equation. Those conditions are given in Table 1. 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.

All the k values default to 1 in the absence of speci?

The are computed using the following equations: SL 5 1 SC 5 1 1 0. The equations derived and documented in standard DIN provides an axes rotation and the logarithmic expansion of the new axes to match that of the spacing of the CIE94 color tolerance formula without the need to make the specimen identi? Thus computed color differences are based only on the Euclidean distance in the DIN99 space. Additionally, the colorimetric spectrometer may units in another system for all colors of specimens.

To- tance in the coatings, plastics, textiles and related industries. The CIELAB position and very narrow bandpass and moderate baseline color-difference equation is also not recommended in this stability.

Colorimetric spectrometers are designed to optimize practice for use in describing small and moderate color their use as digital simulations of the visual colorimeter or as differences differences with magnitude less than 5.

The four more recently defined equations, documented computer-assisted color matching systems. Digital colorimetry here, are highly recommended for use with color-differences in allows more tolerance on the spectral scale and spectral the range of 0. However, for control of color in space, of a reference color, for the purpose of single number production, it may be necessary to know not only the magni- shade passing. Thus, inter-changing the instrumentally determined components of the color difference.

A color difference equation the acceptability of differences in hue, lightness, and saturation quantifies distance in a color space using the metric of that obtained by using Practice D The three tolerance equa- space. Inter-changing the reference and test specimens does not tions given here have been tested extensively against such data change either the perceived or predicted color differences. Summary of Practice visual judgments.

That implies that the equations themselves 4. Reflectance readings 5.

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Good correlation with the visual judg- automatically make the computations. Color-difference units ments may not be obtained when the calculations are made are computed, from these color-scale values, and approximate with other illuminants. Use of a tolerance equation for other the perceived color differences between the reference and the than daylight conditions will require visual confirmation of the test specimen.

Significance and Use 6.

Description of Color-Difference and Color-Tolerance 5. D 11 formed by three rectangular axes representing the lightness 6. The 6. Here sign is a function that returns the sign of the argument, Here, i varies as X, Y, and Z.

The units of hab calculated by the above are nominally white object-color stimulus.The revision published in omitted these sections, and limited the color spaces and color-difference equations considered, to the three most widely used in the paint and related coatings industry. For specimens that are matte, randomly rough, or mildly textured, values intermediate between and can be used, with the value 1.

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The tolerances and differences determined by these procedures are expressed in terms of approximately 2. The object-color stimulus is given by the spectral radiant power of function sign is expected to return a minus one for negative one of the CIE standard illuminants, for example, C, D65 or values of the agrument, a zero when the argument is zero, and another phase of daylight, reflected into the observers eye by a positive one for positive values of the argument.

There should not be a need to break the equation down into perceptual components—the CIELAB components of the model do that already.

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