Abstract

Land’s recent Mondrian experiments¹ are striking demonstrations that colors of objects are largely independent of the wavelength composition of the light incident on them. Attempts to implement this independence in artificial vision systems have renewed interest in color constancy and contrast and the explanation of these phenomena in Retinex theory. We have shown that the color shifts occurring in a Mondrian display are in general much larger than can be tolerated if color constancy were to hold.² Furthermore, the same color shifts were obtained when the complex Mondrian pattern was replaced by a homogeneous gray field surrounding a test patch. Neither the equivalence of this neutral surround nor the color shifts are correctly predicted by the Retinex algorithm.¹ The Land phenomenon of partial cancellation of chromaticity shifts when a change of illuminant reduces to simultaneous contrast, if a spatiochromatic and luminance average over a Mondrian pattern is the same as for a homogeneous surround. Experiments with simultaneous contrast demonstrate that spatial weighting factors are needed in the computation of the combined effect of complex Mondrian patterns.

© 1988 Optical Society of America