Correlation Analysis of Image Reproduction and Display Color Temperature Change to Prevent Sleep Disorder

This paper aims to determine the effect of the smartphone warm color temperature function that relieves display's HEVL (high-energy visible light and short wavelength series blue light), which is known to cause suppression of melatonin secretion on actual image reproduction quality. For this study, the author of this paper measured the display based on the color difference in 26 sampling colors. It was found that for correlated color temperature (CCT) of 4000 K or less, the color difference rose sharply, centering around red and green. In hardware or software, a low CCT was realized by reducing the output centered on blue and green, but in actual color quality, a problem arose in the red and green channels. As far as tone gradation is concerned, ΔE increased for CCT of 4500 K or less while the accuracy of the shadow detail was reduced. With regard to color gamut reproduction, for the coverage of sRGB color space, the color gamut became narrow for CCT of 5500 K or less, and for volume, the color gamut became narrow sharply for CCT of 4000 K. It was found that the maximum CCT changes to prevent a decline in melatonin secretion at a level of minimizing the degradation of image quality is 4000-4500 K.