Discovery of global common denominators of skin reflectance that enhance attractive impressions
-Paradigm shift in benefits of foundations to bring out individual beauty-
Podium 39
Presented by: Ryo Kakimoto
Introduction
In response to the global need to respect diverse individuality in terms of skin features, minds, and social attributes, desirable foundations have changed from those that simply conceal imperfections to those that bring out the beauty in individuality. Previous research with Japanese participants has shown that the spectral reflectance of skin is closely related to the impression it creates [1, 2]. However, previous studies have not been exhaustive in their investigation of global skin tones, due to the limitation of conventional skin tone classification methods based on visible skin colours [3].
In this study, we aimed to comprehensively elucidate the relationship between skin spectral reflectance and impressions for the development of foundations that enhance attractive impressions envisioned by each individual. To achieve this goal, we firstly classified global skin tones using a statistical method based on unique parameters derived from spectral reflectance. Secondly, we investigated the distinctive spectral reflectance pattern that can accentuate a specific impression in the respective skin tone categories, using a multi-wavelength observation room with sixteen narrow-band LEDs that enabled us to evaluate impressions accurately in a real-life space.
Methods
・Global skin tone classification
Thirty-seven characteristic parameters that were defined based on our original hypothesis using the global skin spectral reflectance database (ISO/TR 16066:2003) were subjected to principal component analysis. The principal component scores of 1 to 3 were then used to classify skin tones into six categories, C1 to C6, by hierarchical clustering (Ward method).
・Impression evaluation test
Participants (n=48) covering all six skin tone categories (C1 to C6) were recruited. The spectral reflectance patterns were selected by preliminary studies of 126 patterns. Ten expert evaluators were asked to evaluate the change in impressions when the intensity of each spectral reflectance was altered from the commonly used white LED light (correlated colour temperature: 5000K, hereafter STD). To avoid deviation from the natural skin tone of the participants, the intensity was limited to specific ΔL and ΔE values in comparison with the bare skin tone under STD. For this evaluation, the highest scoring impression items from a questionnaire of global participants (n=3000) were used. Evaluation scores were recorded on a 7-point scale compared to that of STD.
Result and Discussion
Analysis of the relationship between spectral reflectance patterns and impressions revealed for the first time that three types of spectral reflectance pattern can enhance specific impressions common to all skin tone categories. Specifically, PATTERN 1, in which the 595-nm (orange) or 630-nm (red) wavelengths were raised independently, resulted in significantly higher mean values for the "Healthy-looking skin" impression. Furthermore, PATTERN 2, in which the 435 nm (purple) or 455 nm (blue) wavelengths were raised separately, resulted in significantly higher mean values of the "Clear skin" impression. In contrast, PATTERN 3, in which the 455 nm (blue) and 630 nm (red) wavelengths were raised simultaneously, resulted in significantly higher mean values of the "Lively skin" impression. Moreover, we quantitatively identified the optimal intensity ranges of these three patterns respectively for C1 to C6. From these experiments, we succeeded in constructing a comprehensive theory of the relationship between spectral reflectance and impressions with quantitative indicators of optimal intensity ranges for each skin tone category. Application tests using a foundation that was developed based on this theory confirmed that the intended impression was enhanced.
Conclusion
In this study, our investigations led to a new discovery of global common denominators of spectral reflectance patterns that can enhance the attractive impression. We believe this discovery can bring a paradigm shift in benefits of foundations to bring out individual beauty by offering custom-made products that are tailored to the skin conditions and impression preferences. Furthermore, our study becomes an important knowledge not only for make-up products but also for various beauty industries such as skincare, online counselling and residential lighting that contribute to the beauty in individuality.
References
[1] K. Mohri et al., J. Soc. Cosmet. Chem. Japan, Vol. 40, No. 4, 278-286, 2006
[2] S. Yamaguchi et al., Panasonic Technical J., Vol. 58, No. 2, 62-66, 2012
[3] L. Caisey et al., Dermatology for Skin of Color Chapter, Vol. 71, 541-551, 2009
In response to the global need to respect diverse individuality in terms of skin features, minds, and social attributes, desirable foundations have changed from those that simply conceal imperfections to those that bring out the beauty in individuality. Previous research with Japanese participants has shown that the spectral reflectance of skin is closely related to the impression it creates [1, 2]. However, previous studies have not been exhaustive in their investigation of global skin tones, due to the limitation of conventional skin tone classification methods based on visible skin colours [3].
In this study, we aimed to comprehensively elucidate the relationship between skin spectral reflectance and impressions for the development of foundations that enhance attractive impressions envisioned by each individual. To achieve this goal, we firstly classified global skin tones using a statistical method based on unique parameters derived from spectral reflectance. Secondly, we investigated the distinctive spectral reflectance pattern that can accentuate a specific impression in the respective skin tone categories, using a multi-wavelength observation room with sixteen narrow-band LEDs that enabled us to evaluate impressions accurately in a real-life space.
Methods
・Global skin tone classification
Thirty-seven characteristic parameters that were defined based on our original hypothesis using the global skin spectral reflectance database (ISO/TR 16066:2003) were subjected to principal component analysis. The principal component scores of 1 to 3 were then used to classify skin tones into six categories, C1 to C6, by hierarchical clustering (Ward method).
・Impression evaluation test
Participants (n=48) covering all six skin tone categories (C1 to C6) were recruited. The spectral reflectance patterns were selected by preliminary studies of 126 patterns. Ten expert evaluators were asked to evaluate the change in impressions when the intensity of each spectral reflectance was altered from the commonly used white LED light (correlated colour temperature: 5000K, hereafter STD). To avoid deviation from the natural skin tone of the participants, the intensity was limited to specific ΔL and ΔE values in comparison with the bare skin tone under STD. For this evaluation, the highest scoring impression items from a questionnaire of global participants (n=3000) were used. Evaluation scores were recorded on a 7-point scale compared to that of STD.
Result and Discussion
Analysis of the relationship between spectral reflectance patterns and impressions revealed for the first time that three types of spectral reflectance pattern can enhance specific impressions common to all skin tone categories. Specifically, PATTERN 1, in which the 595-nm (orange) or 630-nm (red) wavelengths were raised independently, resulted in significantly higher mean values for the "Healthy-looking skin" impression. Furthermore, PATTERN 2, in which the 435 nm (purple) or 455 nm (blue) wavelengths were raised separately, resulted in significantly higher mean values of the "Clear skin" impression. In contrast, PATTERN 3, in which the 455 nm (blue) and 630 nm (red) wavelengths were raised simultaneously, resulted in significantly higher mean values of the "Lively skin" impression. Moreover, we quantitatively identified the optimal intensity ranges of these three patterns respectively for C1 to C6. From these experiments, we succeeded in constructing a comprehensive theory of the relationship between spectral reflectance and impressions with quantitative indicators of optimal intensity ranges for each skin tone category. Application tests using a foundation that was developed based on this theory confirmed that the intended impression was enhanced.
Conclusion
In this study, our investigations led to a new discovery of global common denominators of spectral reflectance patterns that can enhance the attractive impression. We believe this discovery can bring a paradigm shift in benefits of foundations to bring out individual beauty by offering custom-made products that are tailored to the skin conditions and impression preferences. Furthermore, our study becomes an important knowledge not only for make-up products but also for various beauty industries such as skincare, online counselling and residential lighting that contribute to the beauty in individuality.
References
[1] K. Mohri et al., J. Soc. Cosmet. Chem. Japan, Vol. 40, No. 4, 278-286, 2006
[2] S. Yamaguchi et al., Panasonic Technical J., Vol. 58, No. 2, 62-66, 2012
[3] L. Caisey et al., Dermatology for Skin of Color Chapter, Vol. 71, 541-551, 2009