Display White Points Under Different Ambient Lighting Conditions

The purpose of this study is to investigate the image `white' point on a display under dark environment and different ambient illuminants. A single image composed of black text and white background was used. It was converted by means of the CAT02 chromatic adaptation transform from 6500K and Duv of zero, into 48 different white points varying at 6 CCTs and 8 Duv levels. Through psychophysical experiments, observers' subjective evaluations of neutral white and preferred white for 48 white stimuli were obtained via a pair comparison method. The results showed that the most neutral and preferred image white points were located at 7200K and 6000K respectively in the dark environment, and CCTs ranged from 6600 to 7300K and 5900K to 6300K respectively under different ambient illuminant conditions. It was also found that both the neutral white and preferred white were below the Planckian locus. The chromaticities of the neutral white and preferred white shifted in the same direction with the change of those of ambient lightings. The results can be proposed to achieve visual comfort on mobile devices under various ambient lighting conditions.