Richer Vincent, Kharazmi Pegah, Lee Tim K, Kalia Sunil, Lui Harvey
Department of Dermatology and Skin Science, University of British Columbia & Photomedicine Institute, Vancouver Coastal Health Research Institute, Vancouver, BC, Canada.
Departments of Cancer Control Research Program and Integrative Oncology - Imaging Unit, British Columbia Cancer Agency, Vancouver, BC, Canada.
Photodermatol Photoimmunol Photomed. 2018 Mar;34(2):130-136. doi: 10.1111/phpp.12361. Epub 2017 Nov 20.
There is no accepted method to objectively assess the visual appearance of sunscreens on the skin.
We present a method for sunscreen application, digital photography, and computer analysis to quantify the appearance of the skin after sunscreen application. Four sunscreen lotions were applied randomly at densities of 0.5, 1.0, 1.5, and 2.0 mg/cm to areas of the back of 29 subjects. Each application site had a matched contralateral control area. High-resolution standardized photographs including a color card were taken after sunscreen application. After color balance correction, CIE Lab* color values were extracted from paired sites. Differences in skin appearance attributed to sunscreen were represented by ΔE, which in turn was calculated from the linear Euclidean distance within the Lab* color space between the paired sites.
Sunscreen visibility as measured by median ΔE varied across different products and application densities and ranged between 1.2 and 12.1. The visibility of sunscreens varied according to product SPF, composition (organic vs inorganic), presence of tint, and baseline b* of skin (P < .05 for all).
Standardized sunscreen application followed by digital photography and indirect computer-based colorimetry represents a potential method to objectively quantify visibility of sunscreen on the skin.
目前尚无公认的客观评估防晒霜在皮肤上视觉外观的方法。
我们提出了一种用于涂抹防晒霜、数码摄影和计算机分析的方法，以量化涂抹防晒霜后皮肤的外观。将四种防晒乳液以0.5、1.0、1.5和2.0毫克/平方厘米的密度随机涂抹在29名受试者背部的不同区域。每个涂抹部位都有一个与之匹配的对侧对照区域。涂抹防晒霜后拍摄包括色卡在内的高分辨率标准化照片。在进行色彩平衡校正后，从配对部位提取CIE Lab颜色值。防晒霜导致的皮肤外观差异用ΔE表示，它是根据Lab颜色空间中配对部位之间的线性欧几里得距离计算得出的。
通过中位数ΔE测量的防晒霜可见度因不同产品和涂抹密度而异，范围在1.2至12.1之间。防晒霜的可见度因产品的防晒系数、成分（有机与无机）、是否有色调以及皮肤的基线b*而异（所有P值均<0.05）。
标准化的防晒霜涂抹方法，随后进行数码摄影和基于计算机的间接比色法，是一种客观量化防晒霜在皮肤上可见度的潜在方法。
