Relational colour constancy from invariant cone-excitation ratios

Abstract

Quantitative measurements of perceptual colour constancy show that human observers have a limited and variable ability to match coloured surfaces in scenes illuminated by different light sources. Observers can, however, make fast and reliable discriminations between changes in illuminant and changes in the reflecting properties of scenes, a discriminative ability that might be based on a visual coding of spatial colour relations. This coding could be provided by the ratios of cone-photoreceptor excitations produced by light from different surfaces: for a large class of pigmented surfaces and for surfaces with random spectral reflectances, these ratios are statistically almost invariant under changes in illumination by light from the sun and sky or from a planckian radiator. Cone-excitation ratios offer a possible, although not necessarily unique, basis for perceptual colour constancy in so far as it concerns colour relations.

Spatial and Temporal Properties of Cone Signals in Alert Macaque Primary Visual Cortex

“…These results, using stimuli with gray backgrounds, confirm results using stimuli with different colored backgrounds (Conway, 2001). Such "doubleopponent" receptive fields are ideal substrates for color constancy and color contrast (Hurlbert and Poggio, 1988;Dufort and Lumsden, 1991;Foster and Nascimento, 1994;Gegenfurtner, 2003;Hurlbert and Wolf, 2004), computations that likely involve V1 (Barbur et al, 2004) (but see Zeki et al, 1999). Some doubleopponent receptive fields were circularly symmetric, with round centers and doughnut-shaped surrounds, but most had round centers with crescent-shaped surrounds, or two parallel ovalshaped subfields.…”

Surface gloss and color perception of 3D objects

“…Some of this comes under the rubric of color appearancẽ Wyszecki, 1986;Shevell, 2003! and of color order systems Derefeldt, 1991;Brainard, 2003!. A second literature emphasizes the effects of changing illumination~Helson, 1940; Burnham et al, 1957;McCann, 1976;Arend & Reeves, 1986;Brainard & Wandell, 1992;Foster & Nascimento, 1994;Brainard, 1998;Bauml, 1999;Delahunt & Brainard, 2004;Hansen et al, 2007! or effects of scene geometry on the appearance of flat test surfaces~Bloj et al, 1999;Yang & Maloney, 2001;Khang & Zaidi, 2002;Boyaci et al, 2003Boyaci et al, , 2004Ripamonti et al, 2004!.…”

Does colour constancy exist?

“…The ability of subjects to make accurate relational judgments independent of the illuminant, as with these minimalist scenes, has been attributed to 'relational colour constancy' [28]; that is, the constancy of perceived colour relations under different illuminants. It was initially conceived for situations in which scenes differ only in illuminant, so that one surface could be related to another -the simplest possible comparison.…”

“…Relational colour constancy can be interpreted operationally: subjects are simply asked to discriminate between illuminant and surface-reflectance changes [28,29]. Performance in one such task has been found to be fast, accurate and effortless, suggesting that some aspects of surface-colour information are processed in parallel over the visual field [27].…”