Abstract
A recent computational model of achromatic color perception proposes that gray shades are encoded in a two-dimensional space formed by brightness and darkness dimensions (Vladusich et al., 2007, PloS Comp Biol, 3: e179). This model predicts that achromatic colors should depend on higher-order image statistics, such as the variance, skewness and kurtosis of the luminance values in a scene. I provide perceptual evidence in support of this prediction and link the properties of the model to a recent demonstration that such image statistics play a key role in the perception of matte and glossy surface material (Motoyoshi et al., 2007, Nature, 447: 206–209). The model also makes the testable prediction that neural ON and OFF channels should provide inputs to a two-dimensional spatial map of achromatic colors analogous to the hue maps described recently in primate extra-striate cortex (Conway et al., 2007, Neuron, 56: 560–573).
Supported in part by the National Science Foundation (NSF SBE-0354378).