scope:

This International Standard specifies two illuminants for use in colorimetry. The illuminants, which are defined in clauses 4 and 5 of this International Standard, are as follows: a-CIE standard illuminant A This is intended to represent typical, domestic, 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.