Inner and outer lip contour tracking using cubic curve parametric models

The first step in lip-reading applications is mouth contour extraction to provide a link between the lip shape and the oral message. In our approach, lip contours are detected in the first image with the two algorithms developed and for static images. On subsequent images of the sequence, several key points (mouth corners, inner and outer middle contour points) are tracked with the Lucas-Kanade method to define an initial parametric lip model of the mouth. According to a combined luminance and chrominance gradient, the model is optimized and precisely locked on to the lip contours. The algorithm performances are evaluated with respect to a lip-reading application.