Polygonal approximation of digital planar curves through vertex betweenness

Contour polygonal approximation is usually defined as a set of selected points, which describes a polygon and best represents the original contour. This paper presents a novel graph based approach to compute a polygonal approximation of a shape contour. In a graph, such points correspond to a high transitivity region of the graph. We use the vertex betweenness to measure the importance of each vertice in a graph according to the number of shortest paths where each vertice occurs. By selecting the vertices with higher vertex betweenness, a polygon which retains the main characteristics of the contour is achieved. By using benchmark curves, a comparative experiment with other commonly used algorithms is presented. Results indicate that the proposed approach produced efficient and effective polygonal approximations for digital planar curves.