Skeletonization using the divergence of an anisotropic vector field flow

In this paper we introduce a procedure to obtain both the automatic positioning of an initial contour for edge extraction and a new approach to skeletonize the captured contour. We propose a parametric deformable method that relies on a generalized anisotropic flow for the evaluation of an external force field which will be applied on active contour procedure. Therefore we recur to field divergence to analyze its convergence, in order to better place an initial curve. We put in evidence that the divergence of the vector field satisfies an anisotropic diffusion equation as well. The curves of positive divergence may be thought as propagating fronts of an evolution function. It has been proved that the sets of points in the image domain where divergence assumes positive values, converge to the skeleton of the extracted contour. We suggest that the divergence of a vector field may be an alternative medial axis function as soon the steady configuration of the anisotropic flow has been reached.