Kyungah Choi, a Ph.D. candidate of CED Lab made a presentation entitled, “Recalling white point of smartphone under varying illuminants” on the IS&T/SPIE Electronic Imaging (EI 2014), CA: Burlingame, USA. This study investigated any consistent tendency of people recalling white displayed on smartphones. Jiho Jang, a master candidate of CED Lab assisted the empirical study and thereby a co-author of the conference paper.
The purpose of this study is to achieve color consistency in smartphone displays under varying illuminants focusing on the correlated color temperature of the white point. In the two experiments, asymmetric color matching sessions were conducted, in which subjects were asked to recall a target white point among differently nuanced white colors. In Experiment I (N=58), 6 target white points varying from 5,900 K to 11,300 K, and 15 nuanced white colors varying from 2,700 K to 19,200 K were produced. The recalling test was carried out under 11 illuminants varying between 2,500 K and 19,300 K. Both display white colors and illuminants were divided into intervals of approximately 1,000 K. The study observed a shift in the recall of the target white point. The direction of the shift had a tendency toward higher color temperature. However, when the target white points were between 5,900 K and 8,000 K, the effect of the illuminants on color recall was marginal. In order to confirm the weak effect of the illuminants, Experiment II particularly focused on this color temperature range. 3 target white points were chosen which corresponded to the color temperatures of 6,600 K, 7,000 K, and 7,500 K, respectively. The visual assessment was conducted with a group of graphic design experts, and the 33 nuanced white colors used for the comparison had intervals of approximately 200 K. The study revealed that the maximum shift in color temperature was 294 K, which is in agreement with the result of Experiment I.