Segmentation of human faces in color images using connected operators

In this paper we present a face segmentation algorithm for color images based on connected operators. Using a skin color model, we construct a skin probability image that indicates the probability of each pixel representing skin. Morphological filters are applied to this probability images instead of applying them to the original image. A hierarchy of operators with geometrical criteria (size, compactness, orientation) is employed to simplify the skin probability image and a gray level criterion based on principal components analysis is used for final classification. Using connected operators, regions with different probabilities of being skin are analyzed which leads to a more robust segmentation compared to a single threshold classification