Abstract

In successive color matching of simple uniform colors the precision of the match declines as the time between the presentation of the reference stimulus and the presentation of the test stimulus increases. When the stimulus is more complicated more degrees of freedom must be matched. How does the match precision decline for each degree of freedom? We have examined this question using the most simple fields that are more complicated than uniform colors: grey areas with grey surrounds. Two degrees of freedom characterize the stimuli: the luminance of the center and the luminance of the surround, so the matching precision can be represented by 2-D ellipses similar to the MacAdam ellipses. These ellipses grow in a characteristic way as the time interval increases, elongating along lines of constant contrast. We conclude, at least for these simple images, that the visual system preserves contrast information more precisely than it does overall luminance information. This conclusion has implications for color reproduction, where image and reproduction are generally well separated in time and/or space. Accurate reproduction of contrast is more important for reproduction fidelity than accurate reproduction of overall brightness.

© 1986 Optical Society of America