Adaptive skin-color filter

Abstract

In this paper, we propose a new method, called an adaptive skin color filter, for detecting skin color regions in a color image. The use of skin color provides an efficient way to find candidate regions for faces or hands in color images. However, it is not easy to find skin color regions because the color of skin regions varies from image to image due to a variety of reasons. Since most of the previous methods adopt a fixed threshold scheme, they are useful only in the restricted (i.e., controlled) environment. However, our method is applicable to images in more general situations since it is capable of adaptively adjusting its threshold values and effectively separating skin color regions from similar background color regions. Our method consists of basically two stages. In the first stage, a thresholding box in HSV color space is updated adaptively using a color histogram under the assumption that the area of skin color regions is comparable to that of similar background color ones. In the second stage, color vectors inside the thresholding box are classified into two groups: skin color vectors and background color vectors. Our method and other conventional methods were tested with 379 images obtained from the Internet. Experimental results show that our method is robust to the variations of skin regions’ color compared to the conventional methods.