Smart wavelet image coding: X-tree approach

This paper presents a novel scheme of wavelet image coding, called X-tree coding. An X-tree is defined as a spatial hierarchical tree whose all descendants are insignificant, and it is used to denote 2-D clustered insignificant wavelet coefficients of an image. Two new coding schemes, the progressive X-tree approach and the stack X-tree approach, which are the X-tree versions of the embedded zerotree wavelet (EZW) algorithm and the stack-run coding algorithm, respectively, are proposed. Experimental results have shown that the performances of the proposed algorithms are better than those of the stack-run and the EZW algorithms, and are highly comparable to that of the set partitioning in hierarchical trees algorithm. (C) 2002 Elsevier Science B.V. All rights reserved.