Abstract
Simultaneous contrast refers to the respective brightening (darkening) of physically identical image regions surrounded by neighboring regions of low (high) luminance. A common method of measuring the strength of simultaneous contrast is color matching, in which subjects adjust the luminance of a target region to achieve an achromatic color match with another region. A recent model of model of achromatic color perception suggests that such color matches are relative, rather than absolute, reflecting minimal perceptual distances between colors represented as points in a two-dimensional (2D) color space composed of brightness and darkness dimensions (brightness-darkness space). Here we present psychophysical data supporting this model, and show that achromatic colors are computed as the vector sum of weighted luminance and contrast information in brightness-darkness space. According to the model, simultaneous contrast restricts the color gamut available to subjects performing a color matching task to different 1D slices of brightness-darkness space, with each slice depending uniquely on the luminance values in surrounding image regions. We term this concept gamut relativity.
Meeting abstract presented at VSS 2012