ISO/CIE 11664-2:2022

This document was revised by the International Commission on Illumination (CIE) and is now published in cooperation with Technical Committee ISO/TC 274, Light and lighting, in collaboration with the European Committee for Standardization (CEN) Technical Committee CEN/TC 139, Paints and varnishes, in accordance with the Agreement on technical cooperation between ISO and CEN (Vienna Agreement).
This first edition cancels and replaces ISO 11664-2:2007/CIE S 014-2:2006, which has been technically revised. CIE illuminant D50 has been included as CIE standard illuminant due to its extensive use in the fields of graphic, arts and photography and the references have been updated.
In addition to CIE standard illuminant A and D65, this document also defines CIE illuminant D50 as a new standard illuminant.
a) CIE standard illuminant A
CIE standard illuminant A is intended to represent typical tungsten-filament lighting. Its relative spectral power distribution is that of a Planckian radiator at a temperature of approximately 2 856 K. CIE standard illuminant A should be used in all applications of colorimetry involving the use of incandescent lighting, unless there are specific reasons for using a different illuminant. CIE standard illuminant A is used in photometry as primary reference spectrum for the calibration of photometric devices.
b) CIE standard illuminant D65
CIE standard illuminant D65 is intended to represent average daylight having a correlated colour temperature of approximately 6 500 K. CIE standard illuminant D65 should be used in all colorimetric calculations requiring representative outdoor daylight, unless there are specific reasons for using a different spectral power distribution. Variations in the relative spectral power distribution of daylight are known to occur, particularly in the ultraviolet spectral region, as a function of season, time of day, and geographic location. However, CIE standard illuminant D65 is used pending the availability of additional information on these variations.
c) CIE standard illuminant D50
CIE standard illuminant D50 is intended to represent daylight with a correlated colour temperature of approximately 5 000 K. CIE standard illuminant D50 should be used in colorimetric calculations where the use of such a correlated colour temperature is intended.
Values for the relative spectral power distribution of CIE standard illuminants A, D65 and D50 are given in this document at 1 nm intervals from 300 nm to 830 nm.