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Color perception depends profoundly on adaptation processes that adjust sensitivity in response to the prevailing pattern of stimulation. We examined how color sensitivity and appearance might be influenced by adaptation to color distributions that are characteristic ofnatural images. Color distnl<utions were measured for natural scenes by successively recording each scene with a digital camera through 31 interference filters, or by sampling an array of locations within each scene with a spectroradiometer. The images were used to reconstruct the L, M, and S cone excitation at each spatial location, and the contrasts along three post-receptoral axes [L+M, L-M, or S-(L+M)]. Chromatic contrasts varied principally along a bluish-yellowish axis along which L-M and S-(L+M) signals were highly correlated, with weaker correlations between luminance and chromaticity. We use a two-stage model (von Kries scaling followed by decorrelation) to show how adaptation might influence color appearance by selectively reducing sensitivity to the principal axes of the color distributions, and compare these predictions to empirical measurements of asymmetric color matches obtained after adaptation to successive random samples drawn from natural color distributions.
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