Research of spectrum effects on color visual performance at mesopic condition

This paper studied spectrum effects on color visual performance under mesopic vision. Three types of light sources were studied, namely, high pressure sodium (HPS), phosphor converted white LED and RGB LED. Spectral power distribution (SPD) of HPS had a major peak around 590 nm, the white LED had peaks around 450 nm and 560 nm, the spectrum of RGB LED lamp peaked at 460 nm, 510 nm and 620 nm. The color appearance experiments [1] of those three light sources were carried out at illuminance of 5 lux, 10 lux and 20 lux, including forced judgments of the “most natural” and “most saturating” color appearance of familiar objects, color matching and mesopic color blindness detection. We found that SPD affected the performance of chromatic tasks. In the forced judgment of color appearance, 97% participants characterized white LED and RGB LED as the “most natural”, while 89% characterized RGB LED as the “most saturating [2]”. Color identification accuracy was slightly higher for white LED than that of RGB LED and significantly higher than that of HPS, and it correlated well with the selections of “most natural” and CRI. We also found that speed and accuracy in mesopic color blindness detection were noticeably higher for RGB LED than those of white LED and HPS, they also correlated with the selection of “most saturating” and S/P ratio.