Lip tracking under varying expressions utilizing domain knowledge

In recent years the need of a robust facial component tracking especially lip tracking algorithm has increased dramatically. We implement an active contour (snake) model inspired by human perception for lip tracking. In addition to the conventional energy terms for tension, rigidity (internal energy) and gradient magnitude (external energy) we propose to include energy terms from domain knowledge for lip shape constraint and local region profile constraint. Generalized deterministic annealing (GDA) update of the energy functional helps the solution to escape suboptimal local minima in the energy space and give better tracking result. Experimental results show that the proposed method efficiently adapts to the highly deformable lip boundaries even for lips with indistinct edges and colored (adorned) lips where gradient magnitude based or local region based tracking methods respectively fail. We have done a number of experiments to evaluate the performance of our method in comparison with the existing state-of-the-art methods.