太陽光下における近赤外マルチバンド肌検出手法

Abstract

A skin detection method by using the reflectance characteristics of the human skin in near-infrared ray band has been proposed. This method is one of the robust method to detect the human skin region in real time. However, the human skin may not be detected correctly when the light at unknown spectral ratio of three wavelengths affects it. In order to solve this problem, we introduced IR3 camera which can take three images of near-infrared wavelength, (870nm, 970nm and 1050nm) at the same time. In addition, we used a reference light source at known spectral ratio of three wavelengths. In our proposed method, the effect of the unknown ambient light is suppressed by subtracting images which are irradiated and not irradiated with the reference light source. However the problem with, this method is that the influence of the unknown ambient light is not suppressed under the sunlight. Because the sunlight is a very strong light, and the spectral ratio of the sunlight changes by the minute. In this paper, we divided this problem into two cases to solve this; shadow regions and sunlight irradiated regions. In the case of the sunlight irradiated region, the human skin region is detected by estimating the spectral ratio of the sunlight to equalize the balance of the irradiation of three wavelengths in the sunlight. In the case of shadow region, the human skin is detected by suppressing method of the unknown ambient light. By merging these two results, all of the skin regions are detected under the sunlight.