Amendment of CIECAM02 with a technical extension to compensate Helmholtz-Kohlrausch effect for chromatic characterization of display devices

This paper proposes a method of compensating for the Helmholtz-Kohlrausch (H-K) effect which is a factor not being concerned in CIECAM02. H-K effect refers to the color appearance phenomenon that colored light appears brighter than achromatic light of the same luminance. By the magnitude estimation method, the perceptual lightness of active matrix liquid crystal display (AMLCD) is investigated. The results show that the lightness values predicted by CIECAM02 are lower than perceptual lightness values evaluated by the psychophysical experiments because of the H-K effect. The results on MobileCAM-v2, which is a refined version of CIECAM02, are investigated, as well. Since the color gamut of the display has been widening, the compensation for the H-K effect has also been increasingly important. In this paper, the method to compensate for the H-K effect in CIECAM02 is proposed. By modifying Fairchild's equation, which is previously announced for CIELAB, CIECAM02 can be developed as a more complete color appearance model that can be universally applied to the display devices having a wide color gamut.