Rie OHTSUKI^1,2*, Shoji TOMINAGA², and Osamu TANNO¹

¹Kanebo Cosmetics Inc., Skin Care Research Laboratory, Odawara, Kanagawa 250-0002, Japan ²Graduate School of Advanced Integration Science, Chiba University, Chiba 263-8522, Japan

(Received November 2, 2011; Revised April 23, 2012; Accepted May 23, 2012)

We describe a new method for estimating the concentrations of pigments in the human skin using surface spectral reflectance. We derive an equation that expresses the surface spectral reflectance of the human skin. First, we propose an optical model of the human skin that accounts for the stratum corneum. We also consider the difference between the scattering coefficient of the epidermis and that of the dermis. We then derive an equation by applying the Kubelka–Munk theory to an optical model of the human skin. Unlike a model developed in a recent study, the present equation considers pigments as well as multiple reflections and the thicknesses of the skin layers as factors that affect the color of the human skin. In two experiments, we estimate the pigment concentrations using the measured surface spectral reflectances. Finally, we confirm the feasibility of the concentrations estimated by the proposed method by evaluating the estimated pigment concentrations in the skin.

Key words: pigments, stratum corneum, Kubelka–Munk theory, surface spectral reflectance, oxygenated hemoglobin, melanin

^*E-mail address: ootsuki.rie@kanebocos.co.jp