Code transformations for variant linear quadtrees

Depth-first (DF) and breath-first (BF) linear quadtree representations have the advantages in the performance of image operations and the storage requirements respectively. In this paper, the general guidelines and algorithms for code transformation between BF and DF linear quadtrees are proposed. Thus, we can exploit the advantages of DF and BF representations without suffering their drawbacks. Here, one typical DF linear quadtree scheme (Gargantini, 1982), and two BF linear quadtree schemes with different styles, FBLQ (Chang et al., 1994) with variant length and CBLQ (Lin), with constant length, are selected to depict the guidelines and algorithms. Each algorithm has time complexity O(l), where l is the length of the transformed code. This complexity is much less than that of the BF or DF encoding process for the corresponding image, which is at least of the same order as the number of pixels in this image