A Recursive Chain Code to Quadtree Converting Method with A Lookup Table

Abstract

We present a simple recursive method for converting a chain code into a quadtree representation. We generate the quadtree black nodes recursively from the finest resolution level to the coarsest resolution level. Meanwhile, at each resolution level a new object border is unveiled after the removal of the black nodes. The chain code elements for this new object border can then be easily generated. Thus, the generation of the quadtree black nodes at one level and the generation of the chain code elements of the new object border both constitute a basic cycle of the conversion process. We also show the generations can be done with the aid of a table lookup. Finally, our method is shown to be better than the well-known Samet’s method in terms of the total numbers of major operations including node allocations, node color filling, and node pointer linking.