Revised colour‐appearance model for related and unrelated colours

Abstract To provide a more realistic balance between the relative contributions from cones and rods to the achromatic signal, at various levels of adaptation, revisions have been made to a previously published model of colour vision. Visual areas denoted as the adapting field, the surround, the background, and the proximal field have also been defined. Several minor changes have also been made to make the model more convenient to use. The steps required in using the model are described, and worked examples are included for both related and unrelated colours. For related colours, the differences between the original and revised models are fairly small in the results obtained for samples viewed on grey, or typical average‐scene, backgrounds, at normal photopic levels of illumination, except for lightness and chroma; but for light and dark backgrounds, more wide‐spread changes occur. For unrelated colours, the revised model includes the Bezold‐Brücke dependence of hue on luminance. The predictions given by the model are compared to physiological and psychophysical experimental data.