The Invariance of Colour Perception

In this article the status of colour as an invariant property of objects is addressed. It is explained that if the underlying physical determinants of colour are studied, it will be difficult to consider colour as an internal property of objects. The colour of objects is dependent on both the surface reflectance of incident light and the illumination. Whereas reflectance is a constant factor, the characteristics of the illumination are continuously changing. Therefore, it is surprising that the human perceiver succeeds in assigning colour to objects independent of the illumination. Theoretical developments as well as empirical findings concerning the colour constancy issue are discussed.