Facial Brightness Perception Is Influenced by Hemoglobin and Melanin Modulation

Abstract

A prior study has shown that Japanese people perceive reddish skin as brighter than yellowish skin at the same lightness level. This finding suggests that the perception of facial brightness is not solely determined by physical luminance but is modulated by contextual facial cues such as redness. Specifically, it implies the existence of a perceptual brightness compensation mechanism, in which increased facial redness enhances perceived brightness despite a reduction in colorimetric lightness. Skin color is influenced by melanin and hemoglobin levels, which can affect the perception of facial brightness. Herein, we investigate how changes in these components influence the perception of brightness and color, specifically focusing on the skin of female Japanese faces. Across the experiments, five to six observers participated. Our results showed that simulated increases in hemoglobin or decreases in melanin in facial images enhanced perceived facial brightness. This trend was not observed for uniform color patches with the same average color change as that of the facial images. This finding indicates the existence of a unique visual response to skin pigmentation-driven skin color changes in facial perception.