thinning algorithms have played an important role in the preprocessing phase of OCR systems.. Many algorithms for vectorization by thinning have been devised and applied to a great variety of pictures and drawings for data compression, pattern recognition and raster-to-vector conversion. The vectorization algorithms often used in pattern recognition tasks also require one-pixel-wide lines as input. But parallel thinning algorithms which generate one-pixel-wide thinnings can have difficulty in  preserving the connectivity of an image or generate spurious branches. A few most common thinning algorithms have been implemented and evaluated on the basis of performance parameters.