Quantification of perception towards facial skin ideal complexion in multiple ethnic populations from clinical...

Ideal complexion is a perceptual skin quality that is strongly influenced by cultural and ethnic background. The objectives of this study are to quantitatively characterise skin ideal complexion based on clinical image cues and to compare the perceptions of ideal complexion among multiple ethnicities.

Facial images of Indian, Chinese, Caucasian and Latino females collected using VISIA®-CR were presented to naïve panels of the same ethnicity following a two-alternative forced choice design and responses on skin 'ideal complexion' were obtained from 336 panellists. Panel perception was transformed logistically (d') and projected onto a continuum (ω) following Bradley-Terry model. Image cues including skin colour and unevenness, skin shine and surface smoothness and pigmentary blotches and spots were computed using image analysis, and their relationship with ω was evaluated through multiple regression analysis. A novel skin index, namely ideal complexion score (ICS), was developed and correlated against age using linear regression. Finally, ICS was applied to evaluate treatment efficacy of a skin brightening kit on 35 female Caucasian subjects.

Panel perception d' showed statistically significant (p < 0.05) correlation with the contrast of image cues for all ethnic panels (R²  = 0.74, 0.76, 0.62 and 0.46 for Indian, Chinese, Caucasian and Latino respectively) and strong correlations between perception ω and linear combinations of image cues were observed (R²  > 0.88 for all). Main effects of facial image visual cues on ideal complexion were compared: contrast of skin redness and pigmented spots and visual smoothness were important in determining ICS for all ethnicities; skin colour unevenness was more pronounced for Indian and Caucasian; skin lightness was important for Indian and Chinese; skin shine was critical for Chinese and Latino; and skin hue angle ranked higher for Caucasian. Correlations between ICS and age were observed for Indian and Caucasian (R²  = 0.55) in which ICS decreased as age increased. Twenty-nine percent improvement on ICS was observed after 12 weeks' treatment using the brightening kit compared with the baseline.

Mathematical models were successfully established to describe subjective perception towards skin ideal complexion based on objectively measured image cues for multiple ethnicities.