The analysis and synthesis of human skin color is important in many application areas. The skin color depends on some histological variables such as the concentration of pigments melanin and hemoglobin in skin layers. The present paper proposes a method for estimating the surface spectral reflectance of human skin based on an optics model and applying the estimates to 3D realistic image rendering for a human hand. The human skin is modeled as the two layers of the turbid materials for the epidermis and dermis. An estimation algorithm for the two layer model is then developed using the Kubelka–Munk theory. The parameters representing the concentration of pigments are determined based on spectral reflectance measurements of the human skin surface. In the application step, we describe a technique for rendering realistic skin images of a skin surface as a 3D object. The Torrance–Sparrow model is adapted in the image rendering process. The accuracy of the estimated reflectances is shown in experiments, and skin color images are created under a variety of illumination, viewing, and pigmentation conditions.
Motonori Doi, Norihiro Tanaka, Shoji Tominaga, "Spectral Reflectance Estimation of Human Skin and Its Application to Image Rendering" in Journal of Imaging Science and Technology, 2005, pp 574 - 582, https://doi.org/10.2352/J.ImagingSci.Technol.2005.49.6.art00005