Constructing area Voronoi diagram in document images

Voronoi diagram of image elements provides an intuitive and appealing definition of proximity, which has been suggested as an effective tool for the description of relations among the neighboring objects in a digital image. In this paper, a fast implementation algorithm is proposed for generating area Voronoi diagram of connected components in document images. A closed convex polygon is utilized to bound each connected component, and the contour is represented using Freeman chain coding, from which we can compute the corresponding Freeman chain coding of its expanded contour directly, without recourse to the operation on pixels. While the contours iteratively expand outwards, the Voronoi diagram is constructed by the intersections of the expanded contours from different connected components. The experimental results show that our proposed approach significantly improves the speed of constructing area Voronoi diagram.