【正文】
Line is basic and the most graphic element in engineering forms ma ny high level graphic elements, for example circel, arc. So the quality of line Vectorization is a very important mark in Vectorization performance the bases of analyzing all kinds of lines pixel distribution characteristic, Freeman restriction condition of line chains bees clear. Line Vectorization is the foundation of other graphic Vectorization. This dissertation analyses the feature of lines Freeman chain code, then brings forward a new line Vectorization method based on probability property model including selecting the next line tracking pixel and the first line mergence procedure. This method can satisfy maximum line extending principle , and can reduce line paper realizes the Vectorization of conic , circle and arc using curve fitting method. This line vectorization method can recognise line width order to improve the effect