Effects of adapting luminance and CCT on appearance of white and degree of chromatic adaptation

Past studies reported that the degree of chromatic adaptation was affected by viewing medium and adapting luminance. In this study, human observers adjusted the color appearance of a stimulus produced by a self-luminous display to make it appear as white as possible under different adapting conditions, whose adapting luminance and Correlated Color Temperature (CCT) levels were systematically varied. Though an identical display was used as the viewing medium, the chromaticities adjusted under the high adapting luminance levels were generally around the adapting chromaticities, which was similar to the findings in the past studies using reflective surface color samples as the viewing medium. This suggested that the effect of the viewing medium, as reported in the past studies, was actually the effect of viewing mode, due to the change in adapting luminance. Furthermore, the adapting luminance and CCT were found to jointly affect the degree of chromatic adaptation, with a stronger effect of adapting luminance under a lower adapting CCT.