Researchers from the Toyohashi University of Technology and Kyushu University identified that enhancing high-spatial-frequency components of skin lightness may decrease the perception of facial skin moisture. 

The study involved 3 experiments examining how visual characteristics such as lightness distribution affect perceived hydration levels. The researchers analyzed images of 23 Japanese women using a standardized setup to control light and angles. Observers rated images on a five-point scale for moisture, glossiness, and attractiveness. Fourier Transform techniques were applied to simulate pseudo-drying by enhancing high-spatial-frequency components, emphasizing visual dryness cues like skin streaks.

 In the first experiment, observers rated images on perceived moisture, glossiness, and attractiveness. Perceived glossiness positively correlated with moisture perception. The experiment outcomes showed a sgnificant negative correlation between lightness variance (L*) and perceived skin moisture, particularly in the cheek region.

In the second experiment, image processing techniques, including Fourier Transform, were used to create "pseudo-drying" effects by enhancing high-spatial-frequency components of skin lightness. These manipulations decreased perceived moisture and increased perceived glossiness. The third experiment confirmed the independence of visual perceptions of skin moisture from physiological measurements like transepidermal water loss (TEWL), stratum corneum hydration (SKICON and CORNEO), and oiliness (OIL). No significant correlations were observed between TEWL and perceived hydration. Physical measurements were conducted using standardized equipment (e.g., Corneometer, Sebumeter), and ratings were correlated with visual assessments to ensure consistency.

These findings emphasize the role of visual cues in moisture perception and highlight how manipulating skin lightness features can influence perceptions of dryness or hydration. However, the study’s focus on young Asian observers limits generalizability, and further research is needed across broader demographics,  according to the study published in the Journal of the Optical Society of America A.

This work was supported by JSPS KAKENHI and Pias Corporation. One author is employed by Pias Corporation. No other competing interests were declared.