目的:提供一种面部对比的方法,分析CIELAB颜色差异(ΔEab,10*)及其在来自两个不同种族群体的妇女脸上的成分,由现代白光发光二极管(LED)或国际照明委员会(CIE)推荐的传统光源照明。
方法:我们对87名年轻健康女性(50名白种人和37名东方人)的前额和脸颊进行了分光光度测量,外加五种商业红色唇膏。我们考虑了一组10个白光LED光源,代表目前市场上可用的技术,加上CIE目前推荐的八个主要光源,传统白炽灯的代表,日光和荧光光源。在这18个光源下,我们分析了ΔEab的大小和分量,高加索妇女和东方妇女之间的10*(考虑脸颊和额头),以及高加索和东方女性的脸颊额头和脸颊口红。脸颊的颜色不稳定指数,额头和口红被计算,假设D65和A为参考光源。
结果:ΔEab,在东方人和白种人中,前额和脸颊之间的数量和质量都不同,但是18个光源的平均值差异很小(东方人和白种人分别为1.5%和5.0%,分别)。ΔEab,10*高加索人和东方人之间的前额和脸颊在数量和质量上也有所不同,与平均值的差异再次很小(前额和脸颊分别为1.0%和3.9%,分别)。ΔEab,口红和脸颊之间的10*比额头和脸颊之间的至少两倍高。关于ΔEab,10*口红和脸颊之间,与平均值的差异在1.5%-12.3%之间,尽管对于白色RGBLED发现了高达54.2%的更高值。这种白色RGBLED提供了最高的平均颜色不一致指数:17.1和11.5CIELAB单位,在参考光源D65和A下,分别。
结论:使用特定的白光LED可能会强烈改变女性面部在CIE标准光源下的室外和室内条件下的颜色对比。需要对具有高显色指数的光源的光谱功率分布对化妆品产品的视觉颜色外观的影响进行更多的研究。
OBJECTIVE: To provide an approach to facial contrast, analysing CIELAB colour differences (ΔEab,10∗) and its components in women\'s faces from two different ethnic groups, illuminated by modern white light-emitting diodes (LEDs) or traditional illuminants recommended by the International Commission on Illumination (CIE).
METHODS: We performed spectrophotometric measurements of spectral reflectance factors on forehead and cheek of 87 young healthy women (50 Caucasians and 37 Orientals), plus five commercial red lipsticks. We considered a set of 10 white LED illuminants, representative of technologies currently available on the market, plus eight main illuminants currently recommended by the CIE, representative of conventional incandescent, daylight and fluorescent light sources. Under each of these 18 illuminants, we analysed the magnitude and components of ΔEab,10∗ between Caucasian and Oriental women (considering cheek and forehead), as well as for cheek-forehead and cheek-lipsticks in Caucasian and Oriental women. Colour-inconstancy indices for cheek, forehead and lipsticks were computed, assuming D65 and A as reference illuminants.
RESULTS: ΔEab,10∗ between forehead and cheek were quantitatively and qualitatively different in Orientals and Caucasians, but discrepancies with respect to average values for 18 illuminants were small (1.5% and 5.0% for Orientals and Caucasians, respectively). ΔEab,10∗ between Caucasians and Orientals were also quantitatively and qualitatively different both for forehead and cheek, and discrepancies with respect to average values were again small (1.0% and 3.9% for forehead and cheek, respectively). ΔEab,10∗ between lipsticks and cheek were at least two times higher than those between forehead and cheek. Regarding ΔEab,10∗ between lipsticks and cheeks, discrepancies with respect to average values were in the range 1.5-12.3%, although higher values of up to 54.2% were found for a white RGB LED. This white RGB LED provided the highest average colour-inconstancy indices: 17.1 and 11.5 CIELAB units, under reference illuminants D65 and A, respectively.
CONCLUSIONS: Colour contrasts in women\'s faces under CIE standard illuminants for outdoor and indoor conditions may be strongly altered using specific white LEDs. More research needs to be performed on the impact of spectral power distribution of light sources with high colour rendering indices on visual colour appearance of cosmetic products.