A comment on “a fast parallel algorithm for thinning digital patterns”

A fast parallel thinning algorithm for digital patterns is presented. This algorithm is an improved version of the algorithms introduced by Zhang and Suen [5] and Stefanelli and Rosenfeld [3]. An experiment using an Apple II and an Epson printer was conducted. The results show that the improved algorithm overcomes some of the disadvantages found in [5] by preserving necessary and essential structures for certain patterns which should not be deleted and maintains very fast speed, from about 1.5 to 2.3 times faster than the four-step and two-step methods described in [3] although the resulting skeletons look basically the same.