Skin Color Model
Human skin color has been used and proved to be an effective feature in many applications from human face detection to hand tracking. However, most studies use either simple thresholding or a single Gaussian distribution to characterize the properties of skin color. Although skin colors of different races fall into a small cluster in normalized RGB or HSV color space, we find that a single Gaussian distribution is neither sufficient to model human skin color nor effective in general applications. Further, previous approaches use small collections of images to estimate the density function but do not validate the models by verifying the statistical fit of the chosen model to the data. The work in this chapter is aimed at estimating the properties of human skin color using the Michigan face database (http://www.engin.umich.edu/faces/) which consists of 2,447 images of human faces from different ethnic groups. More than 9.5 million skin color pixels are used to build a skin color model.