What is CIE 1976 (L* a* b*) colour space?
There are perhaps two problems with the specification of colours in terms of tristimulus values and chromaticity space. Firstly, this specification is not easily interpreted in terms of the psychophysical dimensions of colour perception namely, brightness, hue, and colourfulness. Secondly, the XYZ system and the associated chromaticity diagrams are not perceptually uniform. The second of these points is a problem if we wish to estimate the magnitude of the difference between two colour stimuli. The need for a uniform colour space led to a number of non-linear transformations of the CIE 1931 XYZ space and finally resulted in the specification of one of these transformations as the CIE 1976 (L* a* b*) colour space. In fact in 1976 the CIE specified two colour spaces; one of these was intended for use with self-luminous colours and the other was intended for use with surface colours. These notes are principally concerned with the latter known as CIE 1976 (L* a* b*) colour space or CIELAB.
