This CIE standard specifies methods for calculating color values from color stimuli for which the spectral distributions are given. These color stimuli can be generated by self-illuminating light sources or by reflecting or transmitting objects. The standard requires that the color stimulus function be tabulated at measurement intervals of 5 nm or less in a wavelength range of at least 380 nm to 780 nm. Extrapolation methods are suggested for cases in which the measured wavelength range is smaller than 380 nm to 780 nm. The standard method is defined as summation at intervals of 1 nm over the wavelength range from 360 nm to 830 nm. Short methods are defined for larger intervals (up to 5 nm) and smaller ranges (down to 380 nm to 780 nm). The alternative methods should only be used if they are suitable and the user has checked the impact on the final results. The standard may be used together with the colorimetric standard observer CIE 1931 or the colorimetric standard observer CIE 1964.
EN ISO 11664-3:2013 Referenced Document
ISO 11664-1:2007 Colorimetry - Part 1: CIE standard colorimetric observers