ISO 18314-3:2015 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.ISO 18314-3:2015 is applicable to tristimulus values and chromaticity coordinates calculated using colour-matching functions of the CIE 1964 standard colourimetric system. It can be used for the specification of colour stimuli perceived as belonging to a reflecting or transmitting object, where a one-dimensional value is required.