This document specifies different methods of calculating special indices, which are generally used to describe lightness respectively jetness of samples including chroma or hue within one colour-coordinate.

This document is applicable to tristimulus values and chromaticity coordinates calculated using colour-matching functions of the standard colorimetric system of the CIE 1931 (2°) or CIE 1964 (10°). It is used for the specification of colour stimuli perceived as belonging to a reflecting or transmitting object where a one-dimensional value is required.