Visual cues for moisture perception of facial skin: Enhancing high-frequency components of skin lightness increases perceived dryness

Facial skin texture provides crucial visual cues that reflect an individuals impressions and health conditions. In this study, we focused on the texture attribute of "moisture" and investigated which visual cues influenced skin moisture perception. The stimuli consisted of images from three facial areas (the whole face, cheek, and eyebrow areas) with and without makeup under two lighting directions. The participants rated the presented stimuli on the three texture attributes (moisture, glossiness, and attractiveness) using a five-point scale. The results from Experiment 1 revealed correlations between the ratings and histogram statistics of each channel in the CIELAB color space, with variations depending on the conditions and facial regions. A negative correlation was observed between the cheek moisture perception and the variance in the L* channel. We subsequently obtained similar ratings by enhancing the high-frequency components of skin lightness for artificially dried stimuli (Experiment 2) and for images depicting different skin conditions due to various types of makeup (Experiment 3). Both experiments confirmed a decrease in moisture and attractiveness and an increase in glossiness; these were correlated with the degree of artificial drying. These findings indicated that the high-frequency components of skin lightness could be visual cues for determining the perceived dryness.