Lip tracking for MPEG-4 facial animation

It is very important to accurately track the mouth of a talking person for many applications, such as face recognition and human computer interaction. This is in general a difficult problem due to the complexity of shapes, colors, textures, and changing lighting conditions. We develop techniques for outer and inner lip tracking. From the tracking results FAPs are extracted which are used to drive an MPEG-4 decoder. A novel method consisting of a Gradient Vector Flow (GVF) snake with a parabolic template as an additional external force is proposed. Based on the results of the outer lip tracking, the inner lip is tracked using a similarity function and a temporal smoothness constraint. Numerical results are presented using the Bernstein database.