Abstract

Zone theories of the Muller type are major frameworks for psychophysical data on color vision. According to quantitative opponent-color models derived from zone theories, three degrees of freedom given by trichromacy of human photopigments translate into three visual channels. One achromatic or broad-band channel and two color-opponent or chromatic channels. One of the limitations of these models is the absence of explicit spatiotemporal variables in their formulation, in consequence they apply only to data obtained with steady-state aperture colors. Fortunately, a very active area of research is characterized by measurements of spatial and temporal properties of chromatic and achromatic mechanisms and the development of the corresponding theoretical concepts. Within that context, here I summarize two psychophysical studies recently completed: the minimum grating match and measurements of chromatic and achromatic afterimages. Data from the first indicate that the spectral sensitivity of the broad-band channel varies with spatial frequency which is consistent with the current notion that this channel encompasses more than one subsystem; data from the second study are consistent with another current notion: that the r-g color-opponent channel and one of the achromatic subsystems branch out from a common processing stage other than photoabsorption.

© 1992 Optical Society of America