Chromaticities for Producing White Stimuli Depend on Viewing Mode Rather Than Viewing Medium: A Pilot Study

Different chromaticities for producing white appearance were found when viewing color stimuli produced by physical color samples and displays, which has been widely attributed to the different degrees of chromatic adaptation caused by the different viewing media. Here we carried out a pilot study to investigate whether such a difference was caused by viewing medium or viewing mode. Eight human observers adjusted a series of stimuli at six luminance levels that were produced by an iPad display to make them appear the whitest under nine different adapting conditions, with four at a low adapting luminance level and five at a high adapting luminance level. The adjusted chromaticities under the low adapting luminance conditions generally shifted along the Planckian locus toward a higher correlated color temperature (CCT), whereas those under the high adapting luminance conditions were around the chromaticities of the adapting fields. The different chromaticities for producing white appearance under the two adapting luminance levels corroborated the findings in many past studies that used two viewing media (i.e., surface color samples and displays). This suggested that the high adapting luminance level changed the viewing mode of the color stimuli produced by the iPad from the self-luminous mode to the surface mode. Therefore, the different chromaticities for producing white appearance when viewing color stimuli produced by physical color samples and displays should be attributed to the viewing modes instead of the viewing media.