Abstract

By definition, switching a field of a given size between isoluminant colors should trigger no response in the luminance channel. In practice, an exact zero point is not observed, and isoluminance is defined in psychophysics as the point of minimal flicker. Similarly we define ERG-isoluminance as a luminance ratio of two different colors which generates minimal ERG response when alternated. If the ERG were linear and the response wave-forms were independent of color, a luminance ratio must exist where color alternation in a stimulus field elicits no response. However, just as in the psychophysical flicker photometry, a minimum, rather than a response null, is found. This minimum defines ERG-isoluminance. The absence of a null point can be explained by the nonlinearities in the ERG response and difference in wave-form and latencies of the major response components associated with different colored stimuli. In this study deviations from linearity are ignored and only a linear approximation of the response (first order kernel) to luminance and chromatic modulation is considered, as the linear approximation accounted for about 80% of the response power.

© 1992 Optical Society of America