Alexandre Nicolas’s research while affiliated with L'Oréal and other places

Introduction The coverage of a makeup foundation is a perceived attribute which is not captured by opacity or any other single optical property. As previous instrumental measurements do not allow us to consistently compare one product to another, we have begun exploring new parameters and analysis methods made available by hyperspectral imaging. Presumably, the coverage of makeup comes from the change in color, homogeneity, and evenness over the face after application, and the ability of the product to hide spots and other blemishes. Methods As a starting point to unravelling this complex topic, we define a homogeneity factor α H F which measures the change in the homogeneity of the spectra using the distribution of spectral angles in the face. We likewise define a spectral shift factor β S F which indicates the degree of spectral change after product application. To test these new parameters and the overall analysis method, we applied them to the HSI validation dataset which contains data for three makeup foundation products of different coverage levels applied to 9 models. Results We find that α H F correlates with the sensory ranking of coverage. Similarly, the parameter β S F correlates with the visible color change induced by the product, and we can map the three products into distinct categories based on their effect on α H F and β S F . Discussion Nevertheless, the homogeneity factor α H F does not fully describe coverage, and in the variability in the product effect from model to model we find evidence that we must also account for the relative color difference between the model’s skin tone and the product shade among other factors.

Objective: Until now, standardized evaluation of cosmetic effects was conducted mainly in still conditions such as pictures. In real life, the consumers' experience of their cosmetics' effects is dynamic and some of the benefits can be better observed under movement. In order to capture motion-related performance of cosmetics, we developed a video-based paired comparison on an online platform. Methods: We validated this new tool through the evaluation of an eyeshadow with high light reflection and color gradation especially visible under motion according to the observer point of view. This formula was compared with two marketed benchmarks. The three products were applied sequentially on the eyelid of 8 Japanese women. Videos were taken in standardized light, speed and face position with a rotating camera around the face. The videos were uploaded on an online secured platform and eyelid 3D effect, highlight and color gradation were evaluated through paired comparison test by 60 Japanese women from home on their PC or tablets. Those results were compared with picture based paired comparison by the same observers. Results: Video based paired comparison provided higher discrimination of products compared to picture-based comparison. Conclusion: As compared to still camera acquisition, the evaluation of cosmetics based on videos is closer to real life experience and can bring higher discrimination especially for motion-related attributes.

Lastingness is one of the strong needs of consumers for the cosmetics of daytime use, such as sunscreens and foundations. Cosmetic transfer to masks is also an annoying point for consumers even before the COVID-19 pandemic. Various technologies have been developed to solve these needs gaps, but there are still very few environmentally friendly solutions, i.e., with sustainable materials. We developed a technology called PGP (Polyion complex Gel Particles), by introducing dynamic cross-linking to polyion complex using sustainable materials, and applied it to sunscreen BB cream. In vitro and in vivo tests of the formulations and consumer use tests confirmed that the PGP technology provides better color transfer protection and longer-lasting sunscreen efficacy than existing technologies while maintaining usability. This is due to the high encapsulation and film formation abilities of PGP, which allows pigments and lipophilic UV filters to be confined in the cosmetic film, and to the self-recovering function of the cosmetic film thanks to the structural change of PGP through dynamic cross-linking reconstitution. We consider that PGP can solve the strong lasting needs of consumers with an environmentally friendly approach, and is a technology that can be widely applied to different cosmetic products across categories. graphical abstract Fullsize Image

Background Color imaging is a tried and true method for the evaluation of cosmetic and dermatological effects, but it fails to capture all the information in a scene's spectral reflectance. For this reason, there has been in recent years increasing interest in the use of imaging spectrometers for clinical studies and product evaluation. Material and methods We developed a novel HyperSpectral Imager (HSI) able to take in vivo full‐face format images as a next generation instrument for skin color measurement and beyond. Here, we report part of the results of our first full‐scale validation test of the HSI. We replicated a make‐up foundation screening test by applying three products to a panel of 9 models and evaluated the product L∗, a∗, b∗, and ∆E effect immediately after application relative to the bare skin condition. We repeated this test twice in order to study the repeatability of the HSI as an evaluation instrument and during each test two different operators duplicated the data acquisition so we can assess the reproducibility of the measurements. Results We find that the measurements from the HSI provide repeatability and reproducibility as good or better than those of our previous benchmark devices. Conclusion From these results, we conclude that not only is the HSI suitable for use in color evaluation studies, but also that it gives operational advantages over the previous generation of evaluation instruments, as it provides a spectral measurement combined with good spatial resolution. This allows for analysis of color over an area and post hoc selection of study regions and so opens new possibilities for studies of complex in vivo phenomena which neither non‐imaging spectrometers nor conventional cameras can pursue. This study also raises points for future work concerning proper inclusion of instrument uncertainty in comparisons of results between instruments and handling of systematic uncertainties from analyses based on a single area.

Objective: To explore the possibility of an automatic grading algorithm to detect and quantify, from selfies pictures, the subtle changes of facial signs brought by the application of a foundation. Material and methods: 270 Japanese differently aged women (30y to 54y) living in four different Japanese cities took selfies before, immediately and 5 hours after having applied their own foundation, with their own routine. Results: The analysis of 810 selfies pictures revealed (3 times x 270 women) that, prior to applications, all women presented a low grade of facial aging. In most cases, the severities of less marked facial signs, were detected and quantified, found affected by routine at different extents in all age-classes, but more intensely in the older age-class (45-54y) despite their more pronounced signs in bare skin status. In contrast, Periorbital wrinkles were detected as more severe in all age-classes at both timing, i.e., immediately and 5 hours post application as well as Nasolabial folds 5 hours post application. The amplitude of these positive or negative changes, although found of low amplitude, as decimals of the initial grades, were significantly detected. Conclusion: This automatic system appears apt at grading subtle changes in facial aging signs brought by a foundation and could be a valuable help to the consumers of make-up products, in refining their individual procedure to obtain a more personalized desired facial appearance.

Background The concept of hair transparency has been claimed widely in the Japan (and now it is spreading to Asian) hair color market. Despite the general use of this concept, to date, there is no clear and objective description to accurately explain what it is. In this work, we have decoded and gave clarity to the concept of hair transparency via a technical model (validated for both Japan and China markets) composed of measurable parameters of hair property using a single device. Methodology and Results A comprehensive study composed of various tests was used, starting with a qualitative identification of key parameters via in‐depth workshop discussions with over 40 Japanese stylists and a panel of 12 consumers. These identified parameters (luminosity, color visibility, and Shine) were then translated into technically measurable parameters of the hair fiber (Diffused light intensity, ratio of RGB channel intensities of Diffused light, and luster) via a single instrument—Hair SAMBA (a dual‐polarized imaging system). Afterward, 10 carefully selected anchor shades were used as visual stimuli in an online pairwise comparison (PC) study with 100 Japanese stylists to generate quantitative transparency perception data of the swatches. Technical parameters of these swatches were measured by SAMBA and consolidated with the PC output, for the creation and validation of the mathematical model. After, with another PC study (N = 100) in China, with seven shades from Japan study and 6 additional Chinese market shades, the applicability of the model in China market was validated. Conclusion We have clarified and quantified the concept of hair transparency through a consumer centric approach and with objective data. Our findings will enable the development of optimum transparent shades which better suits consumer needs. Lastly, we would like to highlight the beauty of digitalization in the study: The digital evaluation pathways chosen allowed us to collect quantitative consumer data from two countries for the creation of a robust model under the impact of COVID‐19 and would definitely be the way to go for our future consumer evaluation studies.

Background: The recent COVID-19 pandemic has generalized the use of face mask in public area, and it is now common to wear it for long hours. But face mask interfere with cosmetics, and key concerns for tinted products are staining of the mask and degradation on face. Consumers have modified beauty routine by a decrease of makeup, but are now expecting new products adapted to face mask. Little is known about the mechanisms that affect most the makeup under the face mask, so that further studies are needed to develop adequate evaluation methods and products. In this study, the color transfer on mask and makeup degradation on face are assessed through a mixed approach of consumer and instrumental evaluation. Materials and methods: Two tinted face products (A and B) were applied by half face on 11 Japanese women, who conducted real-life activities with a face mask during 4 hours. Panelists evaluated the stain of their face mask by visual assessment, while the makeup degradation on face was evaluated by color measurement by instrumental method. Results: No difference was observed between the two products for lasting on face, but consumer evaluation showed a better resistance of product A for color transfer on mask. Conclusion: The mix of instrumental and consumer evaluation is a promising way to evaluate the makeup degradation on face and color transfer on mask, which are two key factors to develop mask resistant makeup products.

Objective To evaluate the capacity of the automatic detection system to accurately grade, from smartphones' selfie pictures, the severity of ten facial signs in Japanese women and their changes due to age and sun exposures. Methods A three‐step approach was conducted, based on self‐taken selfie images. At first, to check on 310 Japanese women (18‐69 years) enrolled in the northerner Hokkaido area (latitude 43.2°N), how, on ten facial signs, the A.I‐based automatic grading system may correlate with dermatological assessments, taken as reference. Second, to assess and compare age changes in 310 Japanese and 112 Korean women. Third, as these Japanese panelists were recruited according to their usual behavior toward sun exposure, that is, non‐sun‐phobic (NSP, N = 114) and sun‐phobic (SP, N = 196), and through their regular and early use of a photo‐protective product, to characterize the facial photo‐damages. Results (a) On the ten facial signs, detected automatically, nine were found significantly (P < .0001) highly correlated with the evaluations made by three Japanese dermatologists (Wrinkles: r = .75; Sagging: r = .80; Pigmentation: r = .75). (b) The automatic scores showed significant changes with age, by decade, of Wrinkles/Texture, Pigmentation, and Ptosis/Sagging (P < .05). (c) After 45 years, a significantly increased severity of Wrinkles/Texture and Pigmentation was observed in NSP vs. SP women (P < .05). A trend of an increased Ptosis/Sagging (P = .09) was observed. Conclusion This work illustrates, for the first time through investigations conducted at home, some impacts of aging and sun exposures on facial signs of Japanese women. Results significantly confirm the importance of sun avoidance coupled with photo‐protective measures. In epidemiological studies, the AI‐based system offers a fast, affordable, and confidential approach in detection and quantification of facial signs and their dependence with ages, environments and lifestyles.

Objective: To assess the impacts of sun exposures on some skin signs on the faces and hands of differently aged Japanese women, according to their distinct behaviors towards vis à vis sun exposure. Methods: Two comparable cohorts of Japanese women (aged 18-83 y) were created according to their usual behavior towards sun exposure i.e. non-sun-phobic (N = 495) and sun-phobic (N = 516) and through their regular use(s) of a photo-protective product. Standard photographs (full-face and 45° lateral) allowed to focus on 18 facial signs that were graded by 15 experts, using a referential skin aging Atlas. From these two cohorts, two sub-cohorts (114 and 122 women) were created with regard to the similar clinical aspects of the dorsal side of their hands (Left vs. Right) that were further graded. Absolute differences in the scores of each sign were used (non-sun-phobic minus sun-phobic), by age-ranges, to better ascertain the impact of sun exposures and photo-protection. Results: Facial signs related to skin wrinkles/texture and pigmentary spots were found significantly more accentuated among non-sun-phobic women and show an early onset (20-30 years). Facial sagging and crow's feet wrinkles appear delayed (30-40 years). The severity of vascular disorders was found similar in the two cohorts. The absolute differences in the grading's of almost all signs were unsurprisingly found increased with advancing ages, illustrating the combination of chronological and photo-aging processes. With regard to hands, differences in skin texture and pigmentary disorders are of a late onset (40-50 years) and were found much increased at older ages. The cutaneous signs of the hands of Japanese women can hardly be taken as reliable markers of their photo-aging status. Conclusion: The present work illustrates, for the first time, some specificities of the impacts of sun exposures on the facial skin of Japanese women, pinpointing the fact that some facial signs are of an early onset. Results significantly confirm the importance of both sun avoidance coupled with photo-protective measures. This article is protected by copyright. All rights reserved.