This CIE Standard specifies the method of calculating the coordinates of the CIE 1976 L*a*b*
colour space including correlates of lightness, chroma and hue. It includes two methods for
calculating Euclidean distances in this space to represent the perceived magnitude of colour
differences.
The Standard is applicable to tristimulus values calculated using colour-matching
functions of the CIE 1931 standard colorimetric system or the CIE 1964 standard colorimetric
system. The Standard may be used for the specification of colour stimuli perceived as
belonging to a reflecting or transmitting object, where a three-dimensional space more
uniform than tristimulus space is required. It does not apply to colour stimuli perceived as
belonging to an area that appears to be emitting light as a primary light source, or that
appears to be specularly reflecting such light. This Standard does apply to self-luminous
displays, like cathode ray tubes, if they are being used to simulate reflecting or transmitting
objects and if the stimuli are appropriately normalized.
BS EN ISO 11664-4:2011 Referenced Document
CIE 17.4-1987 International Lighting Vocabulary (E) (F) (G) (R)