COLOR APPEARANCE WITH SPARSE CHROMATIC CONTEXT

We compared changes in the appearance of a test region caused by intro ducing an inhomogeneous chromatic background to changes caused by a sp ace-averaged equivalent uniform background, Subjects adjusted a test f ield presented on a CRT so that it appeared neither reddish nor greeni sh, Sparse ''white'' or ''green'' dots, randomly scattered throughout a ''red''' background field, caused a large decrease (up to 15 nm) in the dominant wavelength of the red/green equilibrium setting, compared to measurements with a uniform ''red'' background, A uniform backgrou nd with the same space-averaged chromaticity and luminance as the comp lex background had an effect similar to the uniform ''red'' background , These results contradict theories of color constancy that rely on th e ''gray world'' assumption, and indicate the significance for color p erception of individual chromaticities within discrete, noncontiguous regions.