Enhanced snake model and modified H_∞ for lips contour detection and tracking

An automatic lips contour detection and tracking using an enhanced snake model and modified H_∞ is presented in this paper. For the conventional snakes, the resultant contour would be converged wrongly if the initial snake point is situated far from the lip edges, or with the existence of the tongue and teeth. Consequently, a new external force based on watershed approach is proposed and absorbed into the conventional snake model to deal with the presence of tongue and teeth. Furthermore, a modified H_∞, tracking system is proposed to keep track on the succeeding lips feature points as the initialization of the snake model to detect the lips contour. The modification of the conventional H_∞ is based on the LST to assure that the proposed tracking approach is always stable and as the time approaches to infinity, the tracking error would be converged to zero. With both the modified H_∞ that offer a better tracking capability compared to the conventional H_∞ and the enhanced snakes model with the watershed based external force, the proposed system provide a more precise snakes convergence to the final desired lips contour and the overall simulation results have shown an appreciable performance.