Daylights with high melanopsin stimulation appear reddish in fovea and greenish in periphery

by Hirokuni Higashi, Katsunori Okajima

Melanopsin reportedly contributes to brightness and color appearance in photopic vision in addition to cone photoreceptor cells. However, the relationship between the contribution of melanopsin to color appearance and retinal location is unclear. Herein, we generated metameric daylights (5000 K/6500 K/8000 K) with different melanopsin stimulations while keeping the size and colorimetric values intact and measured the color appearance of the stimuli in the fovea and periphery. The experiment included eight participants with normal color vision. We found that with high melanopsin stimulation, the color appearance of the metameric daylight shifts to reddish at the fovea and greenish in the periphery. These results are the first to show that the color appearance of visual stimuli with high melanopsin stimulation can be completely different in the foveal and peripheral vision even when the spectral power distribution of visual stimuli in both visions is the same. Both colorimetric values and melanopsin stimulation must be considered when designing spectral power distributions for comfortable lighting and safe digital signage in photopic vision.