gusucode.com > 压缩编码效率很高的静止图像压缩编码算法SPIHT,本程序使用matlab实现 > func_MyDescendant.m
function value = func_MyDescendant(i, j, type, m) % Matlab implementation of SPIHT (without Arithmatic coding stage) % % Find the descendant with largest absolute value of pixel (i,j) % % input: i : row coordinate % j : column coordinate % type : type of descendant % m : whole image % % output: value : largest absolute value % % Jing Tian % Contact me : scuteejtian@hotmail.com % This program is part of my undergraduate project in GuangZhou, P. R. China. % April - July 1999 s = size(m,1); S = []; index = 0; a = 0; b = 0; while ((2*i-1)<s & (2*j-1)<s) a = i-1; b = j-1; mind = [2*(a+1)-1:2*(a+2^index)]; nind = [2*(b+1)-1:2*(b+2^index)]; chk = mind <= s; len = sum(chk); if len < length(mind) mind(len+1:length(mind)) = []; end chk = nind <= s; len = sum(chk); if len < length(nind) nind(len+1:length(nind)) = []; end S = [S reshape(m(mind,nind),1,[])]; index = index + 1; i = 2*a+1; j = 2*b+1; end if type == 1 S(:,1:4) = [];; end value = max(abs(S));