Skin coloration is a culturally-specific cue for attractiveness, healthiness, and youthfulness in observers of Chinese and western European descent

The International Skin Spectra Archive (ISSA): a multicultural human skin phenotype and colour spectra collection

This paper presents the International Skin Spectra Archive (ISSA), a multicultural human skin phenotype dataset, containing 15,256 records of both spectral and colorimetric data derived from 2,113 subjects. These measurements, collected between 2012 and 2024, come from eleven different datasets gathered by international laboratories across eight countries, all adhering to a uniform measurement protocol to ensure data consistency. The ISSA dataset addresses the inherent challenges in measuring human skin colour due to its complex structure and covers a wide variability in skin characteristics such as geography, ethnicity, age, gender, and body location. Providing a broad spectrum of human skin data, the ISSA dataset will advance our understanding of skin colour variations and their biological, cultural, and environmental influences. It will also serve as a crucial resource for scientific research and technological development across various fields where diverse and precise spectral and colour data of real human skin are essential.

Ultra-Performance Liquid Chromatography-Quadrupole-Time-of-Flight-Mass Spectrometry-Based Analysis of Facial Physiological Parameters and Lipid Composition of Between Sensitive Skin of Women Aged 36-42 and 43-49 Year

BACKGROUND

UPLC-Q-TOF-MS (Ultra-Performance Liquid Chromatography-Quadrupole Time-of-Flight Mass Spectrometry) is a high-precision, high-density technology for lipid analysis. Sensitive skin is a sub-stable condition, and it has been reported that the population of sensitive skin in China is predominantly female. Meanwhile, women with sensitive skin have different physiological parameters as well as lipid compositions at different ages. The Yellow Emperor's Classic of Internal Medicine states that the number of women's life cycles is seven, that major changes are manifested every 7 years, and that aging begins at age 35. At present, the correlation between facial lipid composition and aging indicators of sensitive skin in women aged 36-42 and 43-49 years has not been reported.

OBJECTIVE

This study reveals the relationship between key lipid composition of the facial skin and the aging of sensitive skin in women aged 36-42 and 43-49 years.

METHODS

We used UPLC-Q-TOF-MS technology to study the changes in lipid composition in the sensitive skin of woman aged 36-42 and 43-49 years, using a multi-probe adapter system with different types of skin-testing probes to test physiological parameters. Three types of multivariate data-questionnaires, physiological indicators, and lipid composition-were used together to assess differences in aging in a population of women with sensitive skin at different ages.

RESULTS

1. In the questionnaire part, the T1 group was more susceptible to sunburn and the T2 group was more susceptible to tanning. 2. In the physiological index part, the aging characteristics of facial skin in the T2 group were obvious, with the b-value, as well as the brown area size, being significantly higher than the T1 group, while the TWEL, sebum, R2 value, ITA value, pore count, and concentration of the red area were significantly lower than the T1 group. 3. In the lipid part, the total facial lipid content was higher in the T2 group, with a significantly higher GP lipid, and the 47 VIP lipids obtained were analyzed by ROC curves, narrowing down to six lipids, PS(2-OMe-21:0/0:0), PS(O-18:0/20:5 (5Z,8Z,11Z,14Z,17Z)), PA(O-16:0/20:5 (5Z,8Z,11Z,14Z,17Z)), PS (P-16:0/12:0, PA (O-16:0/22:2 (13Z,16Z)), and PC (19:3 (10Z,13Z,16Z)/0:0)), and all six lipids were higher in the T2 group. 4. In Spearman correlation analysis, PS(O-18:0/20:5(5Z,8Z,11Z,14Z,17Z)), PS(P-16:0/12:0), PS(2-OMe-21:0/0:0), PA(O-16:0/20:5(5Z,8Z,11Z,14Z,17Z)), and PC(19:3( 10Z,13Z,16Z)/0:0), which are five lipids and skin aging indicators (TWEL, sebum, ITA value, b-value, pore count, concentration of red area, and brown area size) were significantly correlated.

CONCLUSIONS

Through correlation analysis, it was found that changes in the composition of skin surface lipids (SSLs) in both age groups have an important influence on facial physiological indicators (aging manifestations) and played an important role in furthering the understanding of sensitive skin aging. Therefore, these lipid components also provide theoretical support for the development of cosmetic ingredients that slow down the aging of sensitive skin.

The differences in essential facial areas for impressions between humans and deep learning models: An eye-tracking and explainable AI approach

This study explored the facial impressions of attractiveness, dominance and sexual dimorphism using experimental and computational methods. In Study 1, we generated face images with manipulated morphological features using geometric morphometrics. In Study 2, we conducted eye tracking and impression evaluation experiments using these images to examine how facial features influence impression evaluations and explored differences based on the sex of the face images and participants. In Study 3, we employed deep learning methods, specifically using gradient-weighted class activation mapping (Grad-CAM), an explainable artificial intelligence (AI) technique, to extract important features for each impression using the face images and impression evaluation results from Studies 1 and 2. The findings revealed that eye-tracking and deep learning use different features as cues. In the eye-tracking experiments, attention was focused on features such as the eyes, nose and mouth, whereas the deep learning analysis highlighted broader features, including eyebrows and superciliary arches. The computational approach using explainable AI suggests that the determinants of facial impressions can be extracted independently of visual attention.

Cross-cultural comparison of the influence of skin-color change on facial impressions

Skin color is one of the colors we are most frequently exposed to. It contains information, such as ethnic group and health status, and numerous studies have demonstrated the influence of various facial attributes on the formation of impressions. However, no research has specifically explored the repercussions of treating changes in skin color as a singular variable. We cross-culturally examined skin color changes along with the red-yellow axis and how they influence facial impressions across six face shapes from three types of ethnicities. A 7-point scale was used for evaluation, and the observers evaluated the impression of face images according to the following six evaluation items: healthiness, preference, brightness, whiteness, transparency, and skin tone. The observers were divided into the following four groups: Japan, China, Thailand, and the Caucasus. Differences in the evaluation and association of skin color with various traits emerged between cultures. For instance, East Asian cultures associated positive attributes with reddish skin colors, whereas Caucasians often linked positive traits with yellowish skin colors. These cultural disparities emphasize the dynamic interplay between culture and perception in assessing facial impressions.

Variation in Skin Red and Yellow Undertone: Reliability of Ratings and Relevance for Perceived Social Experiences

It is well established that skin lightness-darkness is associated with social outcomes, but little is known regarding the social salience of skin undertones (redness and yellowness). Our study addresses two related research questions on this topic: first, we ask whether red and yellow undertones are consistently perceived by observers; second, we ask whether red and yellow undertones are associated with expectations of discrimination across a range of social settings. We address these questions using novel survey data in which skin lightness-darkness and undertones are captured using CIELAB measurements and a two-dimensional categorical skin color scale. Although we find skin lightness-darkness to be the strongest and most consistent predictor of discrimination expectations, respondents also perceived skin undertones consistently, and skin yellowness was associated with a higher predicted likelihood of discrimination net of lightness-darkness in certain social settings. Our findings suggest that colorism can extend beyond a light-dark binary and emphasize the value of capturing undertones, particularly yellowness, in social surveys assessing skin color.

Yellowness in skin complexion: Analysis of self-perception of women in China evaluated against clinical parameters of yellowness

BACKGROUND

Skin "yellowness" is an abstract and subjective term, without a definitive measurement protocol. Objectives were to analyze Chinese women's self-perception of skin yellowness and associated parameters and identify objective clinical measurements that correlate with these perceptions.

METHODS

Following focus group discussions, criteria for skin yellowness were defined, and validated by volunteer rankings of facial images. A typology study of 185 women was performed. Participants were grouped into yellow (Color Uniformity, Brightness and Transparency (CUBT) yellow scale grade > 3, chromameter b* value > 16) and non-yellow (CUBT yellow scale grade < 2, b* value < 14) groups. Participants self-evaluated their skin on yellowness, transparency, skin uniformity, dullness, radiance, oiliness, and texture. Expert assessments were performed to grade sebaceous pores, ocular area pigmentation, pigmentary spots and CUBT scores. Instrumental analysis of the skin was employed using corneometer, sebumeter, mexameter chromameter, and AGE reader.

RESULTS

Women in the yellow group self-evaluated their skin as significantly duller, less uniform, and less radiant than women in the non-yellow group (P ≤ 0.05). Higher levels of ocular area pigmentation and lower facial skin uniformity and brightness (P < 0.001) were observed in women with yellow skin. CUBT expert grading showed lower pink skin color, but significantly higher beige, yellow, and olive pigmentation (P ≤ 0.05) in women in the yellow skin group. Melanin and b* values were significantly higher in women with yellow skin while L value was significantly lower.

CONCLUSION

Self-perceived skin yellowness in Chinese women correlates to chromameter and mexameter measurements, as well as expert evaluation of ocular pigmentation and CUBT parameters.

Facial Skin Aging Characteristics of the Old-Perceived Age in a 20-40 Years Old Chinese Female Population

Purpose

In the quest for a youthful appearance, women use a variety of anti- aging cosmetics. Defining skin problems is especially important for the selection of anti-aging solutions. However, the skin problems faced by Chinese women at different ages are different. This study aimed at Chinese women aged 20-40 years old and analyzed facial skin aging characteristics of those with old-perceived age.

Patients and Methods

The total of 400 standard facial photographs from Chinese female volunteers aged 20-40 was assessed by another 126 Chinese women. The facial areas and skin aging characteristics that influenced age estimation were collected at the same time. Skin aging characteristics, including wrinkles, skin tone, pigmentation and pores, were analyzed based on facial photographs. Groupings were made based on deviation of perceived age from chronological age, and skin aging characteristics among groups were compared.

Results

The perceived age of Chinese women aged 20-40 has a moderate correlation with chronological age. Women aged 20-30 generally had an old-perceived age. Deep skin tone was a prominent problem in this age group, with those who had the older-perceived age observed the darker and redder skin tone. Women aged 31-40 were perceived partly old but appeared with wrinkle aggravation, as well as deepening of redness, enlarged pores, and increased pigmentation at the mid-face. The perceived older women also had more visible frown lines and darker skin tone at the upper face.

Conclusion

The perceived age of Chinese women aged 20-40 tends to deviate from their chronological age. Women aged 20-30 with old-perceived age are associated with deep skin tone, even found darker and redder in older-perceived women group, while women aged 31-40 are associated with wrinkles and deterioration at mid-face area and upper-face problems drive more attention in older-perceived women group.

Cross-cultural perception of strength, attractiveness, aggressiveness and helpfulness of Maasai male faces calibrated to handgrip strength

Previous research has demonstrated that Maasai and Europeans tend to align in their ratings of the physical strength and aggressiveness of Maasai male faces, calibrated to hand grip strength (HGS). However, perceptions of attractiveness of these faces differed among populations. In this study, three morphs of young Maasai men created by means of geometric morphometrics, and depicting the average sample and two extrema (± 4 SD of HGS), were assessed by men and women from Tanzania, Czech Republic, Russia, Pakistan, China, and Mexico (total sample = 1540). The aim of this study was to test cross-cultural differences in the perception of young Maasai men's composites calibrated to HGS, focusing on four traits: physical strength, attractiveness, aggressiveness, and helpfulness. Individuals from all six cultures were able to distinguish between low, medium, and high HGS portraits. Across all study populations, portrait of Maasai men with lower HGS was perceived as less attractive, more aggressive, and less helpful. This suggests that people from diverse populations share similar perceptions of physical strength based on facial shape, as well as attribute similar social qualities like aggressiveness and helpfulness to these facial images. Participants from all samples rated the composite image of weak Maasai men as the least attractive.

Knowledge, attitude, and practice toward photoaging in the Chinese population: a cross-sectional study

To investigate the knowledge, attitude, and practice (KAP) of photoaging in the Chinese population. This web-based cross-sectional study was conducted between January 2023 and March 2023 among the Chinese population aged 18-80 years old. Participants' knowledge, attitude, and practice toward photoaging were collected through a self-administered questionnaire. A total of 830 questionnaires were collected, with 826 valid questionnaires and an efficiency rate of 99.52%. There were 274 (33.17%) males and 532 (64.41%) aged 31-51 years old. The average knowledge, attitude, and practice scores were 7 (4, 9) (possible range 0-12), 31.5 (28, 34) (possible range 8-40), and 33 (24, 42) (possible range 11-55), respectively, indicating poor knowledge, good attitude, and moderate practice. Spearman correlation analysis showed that knowledge was negatively correlated with attitude (r = - 0.111, P < 0.05) and practice (r = - 0.113, P < 0.05), and attitude was positively correlated with practice (r = 0.992, P < 0.05). The multivariable linear regression model showed that for each point increase in attitude score, the practice score increased by 2.96 points (β = 2.96, 95% CI 2.91-3.01, P < 0.001). The Chinese population has poor knowledge, good attitude, and moderate practice toward photoaging. A good attitude toward photoaging would lead to good practice, and more outreach and education for the Chinese population might be needed.

Predicting Facial Attractiveness from Colour Cues: A New Analytic Framework

Various facial colour cues were identified as valid predictors of facial attractiveness, yet the conventional univariate approach has simplified the complex nature of attractiveness judgement for real human faces. Predicting attractiveness from colour cues is difficult due to the high number of candidate variables and their inherent correlations. Using datasets from Chinese subjects, this study proposed a novel analytic framework for modelling attractiveness from various colour characteristics. One hundred images of real human faces were used in experiments and an extensive set of 65 colour features were extracted. Two separate attractiveness evaluation sets of data were collected through psychophysical experiments in the UK and China as training and testing datasets, respectively. Eight multivariate regression strategies were compared for their predictive accuracy and simplicity. The proposed methodology achieved a comprehensive assessment of diverse facial colour features and their role in attractiveness judgements of real faces; improved the predictive accuracy (the best-fit model achieved an out-of-sample accuracy of 0.66 on a 7-point scale) and significantly mitigated the issue of model overfitting; and effectively simplified the model and identified the most important colour features. It can serve as a useful and repeatable analytic tool for future research on facial impression modelling using high-dimensional datasets.

Let's put a smile on that face-A positive facial expression improves aesthetics of portrait photographs

In today's age of social media and smartphones, portraits-such as selfies or pictures of friends and family-are very frequently produced, shared and viewed images. Despite their prevalence, the psychological factors that characterize a 'good' photo-one that people will generally like, keep, and think is especially aesthetically pleasing-are not well understood. Here, we studied how a subtle change in facial expression (smiling) in portraits determines their aesthetic image value (beyond a more positive appearance of the depicted person). We used AI-based image processing tools in a broad set of portrait photographs and generated neutral and slightly smiling versions of the same pictures. Consistent across two experiments, portraits with a subtle smile increased both spontaneous aesthetic preferences in a swiping task as well as improving more explicit aesthetic ratings after prolonged viewing. Participants distinguished between aspects associated with image beauty and the depicted person's attractiveness, resulting in specific interactions between variables related to participant traits, image content, and task. Our study confirms that a subtle-and in this case fully artificial-smile reliably increases the aesthetic quality of portraits, illustrating how current image processing methods can target psychologically important variables and thereby increase the aesthetic value of photographs.

Method and analysis of color changes of facial skin after applying skin makeup

This study investigated facial skin color differences before and after makeup. Toward this goal, a photo gauge, devised with a pair of color checkers as a reference, collected face images. In addition, color calibration and a deep-learning method extracted the color values of representative areas of facial skin. The photo gauge photographed 516 Chinese females before and after applying makeup. Then, the collected images were calibrated by referencing skin color patches, and the lower cheek regions' pixel colors were extracted using open-source computer vision libraries. Following the visible color spectrum of humans, the color values were computed in L*, a*, and b* of CIE1976L*a*b*. The results showed that the facial colors of the Chinese females changed to become brighter, less reddish, and less yellowish after applying the makeup, resulting in a paler skin tone. During the experiment, subjects were given five varieties of liquid foundation to choose one sample that best fits their skin. However, we failed to find any noticeable relationship between the individual's facial skin color characteristics and the liquid foundation selected. In addition, 55 subjects were identified according to their makeup use frequency and skill, but their color changes did not differ from the other subjects. This study provided quantitative evidence of makeup trends in the Shanghai region in China, and the method proposes a novel approach toward remote skin color research.

An investigation of the influence of skin colour on the perception of femininity, masculinity and likeable

Facial skin colour, a key factor related to impressions, is widely used by CG character designers to build characters with different storylines. The previous research provided essential suggestions for creating an attractive facial image. However, the suggestions of the prior research are insufficient for building the characters to resonate with the current public, especially young people. The present study investigates the influence of skin colour (whiteness and hue angle) on the femininity, masculinity and likableness perception of Chinese female and male images. A psychophysical experiment was carried out to investigate these relationships. The categorical judgement results reveal that whiteness significantly impacted the feminine-masculine perception of the Chinese male image and the likableness perception of the Chinese female and male image. This connection between the whiteness and likability of the male facial image could be related to the beauty trends in the last decade. The hue angle only significantly influenced the likability perception of the Chinese female image. This result is agreed with past research in the same area.

Your face looks the same as before, only prettier: The facial skin homogeneity effects on face change detection and facial attractiveness perception

Previous studies suggested that (1) facial attractiveness perception can be increased with facial skin homogeneity improving; and (2) human's facial change detection increases along with facial skin homogeneity increases. However, it's unknown whether a face can be perceived prettier than it did before while still being considered as physically the same. It is possible that these two kinds of cognitive-aesthetic processing may have separate mathematical functions in psychophysical studies. In other words, human's facial attractiveness differentiation may be more sensitive than facial change detection. In this current study, we explored the above questions. Using three types of psychophysical techniques to manipulate facial skin homogeneity, we measured how participants' sensitivity to facial skin homogeneity and attractiveness change. Results showed a linear function curve for facial physical change detection and a logarithmic function curve was drawn in the forced-choice technique, which was the most sensitive one, indicating that participants can judge a face prettier than before without being aware of it has physically changed. Besides, two linear function curves were shown in the same/different technique and a rating technique. Taken together, this current study revealed that facial attractiveness can be enhanced and discriminated by improving facial skin homogeneity, without being realized by people with conscious awareness that the face has been changed.

Different colour predictions of facial preference by Caucasian and Chinese observers

Facial colour characteristics convey vital personal information and influence social interactions and mate choices as contributing factors to perceived beauty, health, and age. How various colour characteristics affect facial preference and whether there are cultural differences are not fully understood. Here, we provide a useful and repeatable methodology for skin colour research based on a realistic skin model to investigate the effect of various facial colour characteristics on facial preference and compare the role of colour predictors in Caucasian (CA) and Chinese (CN) samples. Our results show that, although the average skin colour of facial areas plays a limited role, together with colour variation and contrast, there are stronger links between colour and facial preference than previously revealed. We also find large cultural differences in facial colour perceptions; Chinese observers tend to rely more heavily on colour and lightness cues to judge facial preference than Caucasian observers.

Preferred skin tones on mobile displays under illuminants having different correlated colour temperatures

A psychophysical experiment was conducted to investigate preferred skin tones of 4 skin types under 5 illuminants varying in correlated colour temperatures. The experiments were performed on calibrated mobile display devices. Four facial skin tone images representing each skin type were captured and were rendered to 25 skin tone images to cover a large colour region. The facial skin tone images were assessed by a panel of 28 Chinese observers using an alternative forced choice psychophysical method. The ellipses based on observer preference rate were derived, and the preferred skin tone centres and 50% tolerance ellipse of different skin types under each test illuminants were obtained. According to the colour appearance shift of preferred skin tones under illuminants with varying CCTs, all data were transformed and compared in the a*b* plane under D65 and CIE 1931 Standard Colorimetric Observer condition. The results on the impact of illuminants on preferred skin tones were reported here. All types of skin tones had a good agreement under different illuminants.