Feature analysis using line sweep thinning algorithm

In this article, we propose a new thinning algorithm based on line sweep op eration. A line sweep is a process where the plane figure is divided into p arallel slabs by lines passing through certain "events." Assuming that the contour of the figure to be thinned has been approximated by polygons, the "events" are then the vertices of the polygons, and the line sweep algorith m searches for pairs of edges lying within each slab. The pairing of edges is useful for detecting both regular and intersection regions. The regular regions can be found at the sites where pairings between edges exist. Inter section regions are those where such relations would cease to exist. A sali ent feature of our approach is that it finds simultaneously the set of regu lar regions that attach to the same intersection region. Such a set is thus called an intersection set. The output of our algorithm consists of skelet ons as well as intersection sets. Both can be used as features for subseque nt character recognition. Moreover, the line sweep thinning algorithm is ef ficient in computation as compared with a pixel-based thinning algorithm wh ich outputs skeletons only.