The role of chromatic scene statistics in color constancy: Spatial integration

The human visual system has the ability to perceive approximately constant surface colors despite changes in the retinal input that are induced by changes in illumination. Based on computational analyses as well as psychophysical experiments, J. Golz and D. I. MacLeod (2002) proposed that the correlation between luminance and redness within the retinal image of a scene is used as a cue to the chromatic properties of the illuminant. However, J. J. Granzier, E. Brenner, F. W. Cornelissen, and J. B. Smeets (2005) found that the spatial extent in the field of vision that is relevant for the effect of the luminance-redness correlation on color appearance is very local and therefore questioned whether this scene statistic is used for estimating the illuminant. Here, I present evidence that the spatial extent is substantially more global than claimed by Granzier et al. and consistent with the hypothesis that this scene statistic is used for estimating the illuminant. It is further shown for two figural parameters of the stimuli that they influence the spatial extent and hence could have contributed to an underestimation of the spatial extent by Granzier et al. Finally, it is shown that the spatial extent relevant for the effect of mean surround chromaticity on color appearance is very similar to that found for the luminance-redness correlation.