Abstract

In this paper, we propose a general Eulerian framework for region-based active contours named DREAM2S. We introduce a general criterion including both region-based and boundary-based terms where the information on a region is named “descriptor”. The originality of this work is twofold. Firstly we propose to use shape optimization principles to compute the evolution equation of the active contour that will make it evolve as fast as possible towards a minimum of the criterion. Secondly, we take into account the variation of the descriptors during the propa- gation of the curve. Indeed, a descriptor is generally globally attached to the region and thus “region-dependent”. This case arises for example if the mean or the variance of a region are chosen as descriptors. We show that the dependence of the descriptors with the region induces ad- ditional terms in the evolution equation of the active contour that have never been previously computed. DREAM2S gives an easy way to take such a dependence into account and to compute the resulting additional terms. Experimental results point out the importance of the additional terms to reach a true minimum of the criterion and so to obtain accurate results. The covariance matrix determinant appears to be a very relevant tool for homogeneous color regions segmentation. As an example, it has been successfully applied to face detection in real video sequences.