The CIELAB colour model was defined in 1976 by the Commission Internationale de l’Eclairage and describes all colours that can be perceived. It is a mathematical colour model in which the spectral properties of an object and the perceptual properties of our visual system are set off against each other. CIELAB, or in short: LAB, has become generally accepted until today wherever exact colour calculation is required, whether in colour measurement, colour formulation or in the common operating systems: Colour management usually works via CIELAB.