A flexible zerotree coding with low entropy

WC introduce a new zzrotree scheme that e&tively exploits the inter-scale self-similaritizs found in the octave decomposition hy a wavelet transform. :2 zerotreti is useful to code wavelet coefiicients and its 4&tiveness wa.q proved hy Shapiro’s I:%W. In the coding scheme. wavzlz~ uoellicients are symholizsd and then entropy-coded. ~fhe entropy per symbol is determined from the produced symbols and the linal coded size is calculated hy multiplying the entropy and the total numher ol‘symhols. In this paper, we analyze symbols produced from the li%W and discuss the entropy per symbol. Since the entropy depends on the produced symbols, we mod@ the procedure of symbol generation. First, we extend the relation between a parent and children used in the EZW to raise the probability such that a significant parent has significant children. ‘I’he proposed relation is flexibly e.xtended according to the tict that a significant coolticisnt is likely to hay< significant coetficients in i& neighborhood. Our coding results arc compared with the puhlishcd rzsul& in paper 1 I I and improvcmsnts come‘ Tom the USL‘ ol’ lower tmtropy per symbol. WI: also giw the comparison ofthz number ol’produced symbols. KEYWORD: image compression, wavelet transform, zerotree coding