Effect of Colored Lights and Illuminance Levels on Subjective Contrast between Chromatic Patches and Achromatic Backgrounds

Abstract

This study aimed to investigate the effect of colored lights and illuminance levels on subjective contrast between chromatic patches and their achromatic backgrounds. It also aimed to examine whether the color difference in CIECAM02 explains the subjective contrast under each lighting condition. We defined the subjective contrast as the subjective and comprehensive differences between a patch and its background. We carried out an experiment under the conditions of combinations of six types of colored lights and five illuminance levels, in which subjects selected the combination of an achromatic patch and its achromatic background that had the same visual difference between a chromatic patch and its achromatic background. The color difference of the selected achromatic combination was defined as the equivalent color difference. The relation between the equivalent color difference and the color difference in CIECAM02 under each lighting condition was clarified. Under white, red, green, or yellow light and illuminance levels of 30 lux or more, subjective contrast was explained by the color difference in CIECAM02.