SPEEDING-UP IMAGE ENCODING TIMES IN THE SPIHT ALGORITHM

In this paper, a new approach (scheme) to the analysis of quad-trees in the discrete wavelet spectrum of a digital image is proposed. During the pre-scanning phase, the proposed scheme generates problem-oriented binary codes for the whole set of quad-tree roots (wavelet coefficients) and thereby accumulates information on the significance of respective descendants (wavelet coefficients comprising quad-trees on the view). The developed scheme can be efficiently applied to any zero-tree based image coder, such as the embedded zero-tree wavelet (EZW) algorithm of Shapiro and set partitioning in hierarchical trees (SPIHT) by Said and Pearlman. Fairly impressive performance of the proposed quad-tree analysis scheme, in the sense of image encoding times, is demonstrated using the SPIHT algorithm and the discrete Le Gall wavelet transform.