scope:

Provides a method of calculating the colour difference between two specimens of the same material, measured under the same conditions, such that the numerical value for the total colour difference quantities the extent to which the two specimens do not match. It permits the specification of a maximum value (tolerance) which depends only on the closeness of match required for a given end-use and not on the colour involved, nor on the nature of the colour difference. The method also provides a means for establishing the ratio of differences in lightness to chroma and to hue.