An adaptive algorithm for conversion from quadtree to chain codes

An adaptive algorithm is presented for converting the quadtree representation of a binary image to its chain code representation. Our algorithm has the advantage of constructing the chain codes of the resulting quadtree of the Boolean operation of two quadtrees by re-using the original chain codes. This algorithm is adaptive because it can adjust the total number of internal nodes to be stored and retrieve it later in the reconstruction stage. The algorithm possesses parallelism and is suited for pyramid architecture. Our algorithm requires time O(H# ̧) in sequential and time O(N) in parallel, where H is the height of the quadtree, ̧ is the length of the chain code sequence generated, and N]N is the size of the input image. ( 2001 Pattern Recognition Society. Published by Elsevier Science Ltd. All rights reserved.