Achromatic color vision-II: Measurement of simultaneous achromatic contrast within a bidimensional system

Abstract

In the previous paper it was shown that more than a single variable is involved in the simultaneous contrast effect, and it was shown that the effect could be accounted for within a bidimensional system of achromatic colors. In the present paper the contrast effect was measured with reference to this bidimensional system. The results show that different combinations of test and inducing luminance produce uniquely different achromatic colors of the test field. Although the different combinations could give the same achromatic quality, or the same color strength, they could not give both together. The results are related to the question of color constancy, and it is shown that there is a consistent relationship between albedo and achromatic quality, and between illumination and color strength. Hence, achromatic color vision provides independent information about albedo and illumination through the two different aspects of achromatic colors, achromatic quality and color strength.