A measurement of the adaptation of color vision to the spectral environment

Steven M. Boker

Department of Psychology The University of Virginia Charlottesville, Virginia 22903

Abstract:

A factor analysis of the reflectance spectral distributions of a sample of natural and man--made objects yields a factor pattern remarkably similar to psychophysical color matching curves. The goodness of fit indices from a maximum likelihood confirmatory factor model with fixed factor loadings specified by empirical trichromatic color matching data indicate that the human visual system performs near to an optimum value for an ideal trichromatic system composed of three linear components. An unconstrained four factor maximum likelihood model is found to fit better than a three factor unconstrained model, suggesting that a color metric may be better represented in four dimensions rather than in a three dimensional space. This fourth factor can be calculated as a nonlinear interaction term between the first three factors; thus three retinal color receptors are sufficient to compute a perceptual color space of four dimensions. The visual system may exploit this nonlinear dependency in the spectral environment in order to obtain a fourth factor without the biological cost of a fourth color receptor.