Abstract
We previously reported that color appearance between different devices can be perfectly matched when the spectral distributions are equal whereas metameric color matching mostly failed. In this study, we prepared custom-made 5D metamers whose stimulus values of three-types of cones, rod, and melanopsin cells were the same as those of reference stimuli for individuals, and we tested whether color appearances of the test and reference stimuli are matched or not. To derive spectral sensitivity functions considering individual optical characteristics, we developed an equipment consisting of an integrated sphere and 10 types of LED elements, and measured several parameters determining spectral sensitivity of each participant under a “2-degree visual angle” condition for estimating individual cone spectral sensitivities, and a “2-degree visual angle with a circular mask of 1.25-degree visual angle” condition for estimating individual melanopsin and rod spectral sensitivities. Next, we set up an equipment with a multi spectral light source, and conducted an experiment in which the color appearance of nine kinds of metamer stimulus pairs were compared. Results show that the color appearance of 5D metamers including rod and melanopsin based on CIE spectral sensitivity functions could not be matched. However, color appearances of custom-made 5D metamers were the same as the reference stimuli even if the spectral distributions were different. These results indicate that individual calibration of spectral sensitivities is essential for precise color appearance evaluation. In addition, the results show that color appearances of custom-made 3D metamers for cones with different rod or melanopsin response were not identical, suggesting that rod and melanopsin cells contribute to color appearance at the central two degrees.