306 JOURNAL OF COSMETIC SCIENCE condition that was closer to the ideal complexion. Pigmentary spots (higher daStar and dbStar), on the other hand, affected panel preference negatively, with more visible dark spots leading to a skin condition deviating further from the ideal complexion. Skin attributes of SVS, CUE, DRR, and HUE contributed to the complexion-preference model minimally without high enough statistical significance, as shown in Figure 7E–H. By scaling the linear model of Figure 6 to a consumer-relevant scale of 0 to 10 and defining it as ICS, a final model was obtained, as shown by Equation 3, which can predict the ICS of a person’s skin based on the objectively measured skin attributes. The properties of the coefficients a, b, C i ,and parameters P i in Equation 3 are listed in Table V. Since the ICS was defined as the relative preference to ideal complexion between two images in a pair, higher values of ICS indicated a skin with conditions that were closer to that of ideal complexion. Equation ICS a C C P b i i i 3. 0 =++=1 Σ4 COMPARISON BETWEEN ICS AND CLINICAL TRANSLUCENCY SCORE Comparing ICS scores with the clinically graded skin translucency scores of the 36 subjects, we observed some similarities. Skins with high ICS scores were generally more translucent, and vice versa, as shown by the correlation plot in Figure 8. This result may have been driven by the pursuit of lighter skin tone in Asian culture, causing the two parameters to overlap. However, since the defining parameters and the mechanisms of synthesizing each parameter were different, they reflect different properties of skin, translucency, and complexion. Figure 6. Correlation plot between actual and predicted Bradley–Terry Probability Ranks, which reflected the relative levels of panel preference to ideal complexion among study subjects. Actual: Bradley–Terry Ranks obtained from transformation of Logit(A) values. Predicted: Bradley–Terry Ranks calculated from the combined effects of basic skin parameters of study subjects.

307 Characterizing and Modeling Complexion Figure 7. Leverage plots showing the effect of individual contributing factor on panel preference to ideal complexion: (A) effect of the lightness of skin tone (B) effect of skin shine (C) effect of red spot severity (D) effect of dark spot severity (E) through (H) are for skin attributes that do not show significant contribution to the panel-preference ranks.