Recommended colour-inconstancy index

One of the parameters of greatest interest in the design and production of coloured objects is their colour (in)constancy, i.e, their change in colour appearance with change in illuminant. Serious practical problems attend th e visual assessment of colour inconstancy. Several instrumentally based mod els have been proposed but none has proved sufficiently reliable for routin e use in the coloration industries. The Colour Measurement Committee (CMC) recommends a recently developed method, named the CMC 1997 colour-inconstan cy index, which is based on a chromatic adaptation transform, CMCCAT97, tha t outperforms all others and is being increasingly adopted in international standards. This paper summarises the development of CMCCAT97 and the resul ts of its testing, and gives details of the calculations necessary to CMCCA T97 and the new colour-inconstancy index.