Polygonal approximating algorithm of digital curves for bitmap laser marking

A bitmap laser marking method based on bitmap vectorization was developed to overcome the difficulties of traditional bitmap marking method used in a laser marking system. In this method, the edge or skeleton of the bitmap was extracted in the form of digital curves firstly, then the polygonal approximating method was adopted to vectorize above digital curves, finally the vectorized data was engraved by means of continuous marking method. The involved algorithm of polygonal approximation of digital curves, consisting of Freeman chain code generating, approximate digital straight line segments extracting and polygonal approximating, was emphatically discussed. The experimental results show that the approximating algorithm works well. The practical application shows that the precision and the speed of bitmap marking can be largely improved with this marking method.