A search algorithm for skeletonization of thick patterns

Abstract An algorithm is proposed in this paper for obtaining the "medial line" or the "skeleton" of a thick pattern. The method introduces new concepts of a "turning point" and an "end point." The present method for thinning binary patterns is a two stage process. During the first stage the method employs four different pairs of operators to test and indicate the existence of vertical, horizontal, right and left inclined limbs in the pattern and to extract the respective end and turning points. During the second stage the medial line of the pattern is obtained by constructing the limbs from a knowledge of the already extracted end and turning points by a simple search procedure. The results obtained by the present method on hand printed alphanumerics are better than those obtained by the existing methods, The extraction of turning and end points also facilitates coding and easy recognition of the given patterns. These results will be reported elsewhere.