Abstract
It has been reported that object and luminous colors cannot be matched in many situations even though their tristimulus values are identical. To clarify whether ipRGCs and/or rods affect such color matching between different color modes, participants compared color appearances of a color patch and a color on an LCD monitor using their central vision. They responded whether the appearances of two colors are the same or not. When the answer was “different”, participants responded the color appearances using an elementary color scaling method. The visual size of each stimulus was 2-deg, the xy-chromaticity values were (0.347, 0.358) and the luminance value was 100 cd/m2. We used a multispectral light source (OL490) for illuminating the color patch which enables to generate an isometric color pair. We prepared 5 conditions: (1) Isometric color match where two spectral distributions were identical, (2) Metameric color match including ipRGCs and rods, (3) Metameric color match including ipRGCs response but not rods response, (4) Metameric color match including rods response but not ipRGCs response, and (5) Metameric color match with different ipRGCs and rods responses. The results under the condition (1) showed that all participants responded that color appearances of the object and luminous colors were perfectly identical, indicating that there exists no color-mode problem when both spectral distributions are identical. On the other hand, the results under the condition (2) showed that some participants responded that color appearances of the object and luminous colors were different, suggesting that there are individual differences on sensitivities of photo-receptors. Compared results of the elementary color scaling under the conditions (2)–(5) revealed that ipRGCs and rods contribute to color appearance. We concluded that the color-mode problem is caused by the individual differences on sensitivities of photo-receptors as well as the contributions of ipRGCs and rods to color appearance.
Acknowledgement: This work was supported by JSPS KAKENHI Grant Numbers 15H05926 and 18H04111.