297 J. Cosmet. Sci., 73, 297–313 (September/October 2022) Address all correspondence to Di Qu, dqu1100@comcast.net Characterizing and Modeling Complexion by Panel Perception and Objective Measurement of Skin Attributes From a Chinese Population DI QU, JIANWEI LIU, ZIQI WU, YINBEI CHEN, XIAOJUAN WANG AND SARAH WHITEHEAD Amway Innovation &Science, Ada, Michigan, USA (D.Q., Z.W., S.W.) Amway Innovation &Science – East Hub, Shanghai, China (J.L., Y.C., X.W.) Accepted for publication December 05, 2022. Synopsis Complexion is one of the top qualities of facial skin, which reflects conditions of health, beauty, and attractiveness. The objectives of this study were to characterize the many facets of complexion, leading to a better understanding and quantification of perceived beauty. This study examined the skin of 36 Chinese women by capturing their facial images, obtaining the opinions of “perceived ideal complexion” from 77 Chinese female panelists through paired comparison, analyzing multiple skin-surface parameters including color and textural properties, and constructing a mathematical model by statistical analysis. It was observed that skin tone and shine positively affected the perception of complexion, while pigmentary discoloration had a negative effect. A skin parameter, Ideal Complexion Score (ICS), was defined by a mathematical model that correlated complexion with basic skin properties. The model can be used to predict ICS scores from skin images. Applying the model to facial image analysis of 480 Chinese women, we show a normal distribution of ICSs in the population at large. The model was also applied to evaluating the treatment efficacy of a skin- lightening ingredient. A statistically significant improvement in ICS over the baseline was detected from the clinical images of study volunteers after 4 weeks’ use of the test formulation. INTRODUCTION A beautiful complexion is in the eye of the beholder. It is one of the top qualities of facial skin that reflects conditions of health, beauty, attractiveness, and even social status in some cultures (1–6). However, the concept of such a skin quality is often subjective and has not been rigorously quantified. Since complexion strongly relates to skin color, its perception is highly influenced by culture and ethnic background (7–14). While people in one part of the world enjoy sunbathing and pursue a tanned appearance, people in another part of the world would go extra miles to avoid exposure to the sun. Their perceptions toward “what ideal complexion is” are obviously different. Complexion is also easily affected by factors such as lack of sleep (15,16). Knowing the beauty industry strives to provide products to

298 JOURNAL OF COSMETIC SCIENCE meet the needs of skin-color management in global markets, we find it is essential to have adequate understanding of ideal complexion perceived by various cultures or ethnicities. Studies on skin complexion relevant to health and beauty industries have been extensive. Considered a major visual cue of overall health, complexion has been thoroughly studied in traditional Chinese medicine as one of the four primary diagnostic means, which has triggered active research in last decade on modern, computerized measurement technology to assist with disease diagnosis (3,17–22). The properties of complexion measured in those studies were mainly color related. In the beauty and skincare industry there are a variety of techniques for skin-complexion assessment ranging from clinical grading to image analysis, and the evaluation of skin-color properties is the primary focus (4,23–27). There were also studies that considered skin properties other than color, such as skin transparency, moisture, surface texture, and evenness of skin tone, to be important factors contributing to the human perception of complexion in a beauty/skincare context (28,29). Intrigued by what we noted in literature, we believed that a systematic study on the perception of ideal complexion was needed. By comparing panel perception results against objectively measured skin properties, we aimed to reveal what consumers were truly paying attention to when perceiving someone’s complexion and to unveil the critical facial skin features that helped drive such preference decisions. The current study was inspired by previous research during which we investigated skin translucency in a group of Chinese women. Being a subjective, consumer-perceivable skin property, translucency has been appreciated very much in Asian societies. We concluded from our prior study that skin translucency possessed combined properties of multiple skin attributes including color, texture, color uniformity, and subsurface light reflection. An excellent correlation was shown between the panel-perceived and the model-predicted levels of skin translucency (30). These results provoked us to investigate whether another consumer-perceived skin property, namely ideal complexion, could be characterized and modeled following a similar mathematical approach. This study is our first attempt to characterize and model ideal complexion by panel perception and objective measurement of skin attributes in a Chinese population. Results of our comparison studies on ideal complexion of four ethnic populations have recently been published (31). MATERIALS AND METHODS SUBJECTS, EXPERT GRADING, AND SKIN-COLOR MEASUREMENT To characterize and model ideal complexion, we used images from the above-mentioned skin- translucency study during which 36 female Chinese subjects, aged 18 to 65 years old, were selected from a group of 120 volunteers in a screening phase to represent a wide range of clinical translucency scores. The study was conducted in our skin testing facility in Shanghai, China, where the subjects were instructed to wash their faces with a mild cleanser in the lab and to acclimate under the controlled room temperature (21 ± 1°C) and humidity (50 ± 5%) conditions for 15 minutes before evaluation. Skin translucency score was clinically graded on the face by a dermatologist whose knowledge about the subject matter was based on professional training, daily experience, and the common understanding of Asian societal and cultural background. Clinical translucency score was defined as the combined effects of multiple skin parameters including surface texture, skin moisture level, color, and skin tone evenness. A 10-point scale was used