UNE-EN ISO/CIE 11664-5:2025

This part of ISO/CIE 11664 specifies the method of calculating the coordinates of the CIE 1976 L*u*v*colour space including correlates of lightness, chroma, saturation and hue. It includes two methods forcalculating Euclidean distances in this space to represent the relative perceived magnitude of colourdifferences. It also specifies the method of calculating the coordinates of the u2 ,v2 uniform chromaticityscale diagram.This part of ISO/CIE 11664 is applicable to tristimulus values calculated using the colour-matchingfunctions of the CIE 1931 standard colorimetric system or the CIE 1964 standard colorimetric system.This part of ISO/CIE 11664 may be used for the specification of colour stimuli perceived as belongingto a reflecting or transmitting object, where a three-dimensional space more uniform than tristimulusspace is required. This includes self-luminous displays, like computer, television and smart-phonedisplays, if they are being used to simulate reflecting or transmitting objects and if the stimuli areappropriately normalized. This part of ISO/CIE 11664, as a whole, does not apply to colour stimuliperceived as belonging to an area that appears to be emitting light as a primary light source or thatappears to be specularly reflecting such light. Only the u2 ,v2 uniform chromaticity scale diagram definedin 4.1 and the correlates of hue and saturation defined in 4.3 apply to such colour stimuli.