A modified contour generation thinning algorithm

A modified contour generation thinning algorithm is proposed. It uses three pieces of information to process a contour pixel, compared with four in the case of the original algorithm and nine in the case of a typical sequential or parallel algorithm. This is possible because of the sequential nature of the algorithm, so that as far as a contour pixel is concerned, its predecessor does not take part in the computation of the new contour. Rather, the directions of the contour pixel with respect to the last generated pixel are used. This information together with the status of the contour pixel and its chain code will enable the new contour to be generated. This modification led to a reduction in coding effect, while maintaining the same speed as the original algorithm