www.pudn.com > SPIHT(Matlab).rar > func_DWT.m

function [I_W , S] = func_DWT(I, level, Lo_D, Hi_D); 
%通过这个函数将I进行小波分解，并将分解后的一维向量转换为矩阵形式 
% Matlab implementation of SPIHT (without Arithmatic coding stage) 
% 
% Wavelet decomposition 
% 
% input:    I : input image 
%           level : wavelet decomposition level 
%           Lo_D : low-pass decomposition filter 
%           Hi_D : high-pass decomposition filter 
% 
% output:   I_W : decomposed image vector 
%           S : corresponding bookkeeping matrix 
% 
% please refer wavedec2 function to see more 
% 
% Jing Tian 
% Contact me : scuteejtian@hotmail.com 
% This program is part of my undergraduate project in GuangZhou, P. R. China. 
% April - July 1999 
 
[C,S] = func_Mywavedec2(I,level,Lo_D,Hi_D);  
 
S(:,3) = S(:,1).*S(:,2);        % dim of detail coef nmatrices 求低频和每个尺度中高频的元素个数 
%st=S(1,3)+S(2,3)*3+S(3,3)*3;%%%%对前两层加密 
%C(1:st)=0; 
 
L = length(S); %a求S的列数 
 
I_W = zeros(S(L,1),S(L,2));%设一个与原图像大小相同的全零矩阵 
 
% approx part 
I_W( 1:S(1,1) , 1:S(1,2) ) = reshape(C(1:S(1,3)),S(1,1:2)); %将LL层从C中还原为S(1,1)*S(2,2)的矩阵 
 
for k = 2 : L-1   %%%%%%%%%%%%%%%%%%%%%%将C向量中还原出HL,HH,LH 矩阵 
    rows = [sum(S(1:k-1,1))+1:sum(S(1:k,1))]; 
    columns = [sum(S(1:k-1,2))+1:sum(S(1:k,2))]; 
    % horizontal part 
    c_start = S(1,3) + 3*sum(S(2:k-1,3)) + 1; 
    c_stop = S(1,3) + 3*sum(S(2:k-1,3)) + S(k,3); 
    I_W( 1:S(k,1) , columns ) = reshape( C(c_start:c_stop) , S(k,1:2) ); 
 
    % vertical part 
    c_start = S(1,3) + 3*sum(S(2:k-1,3)) + S(k,3) + 1; 
    c_stop = S(1,3) + 3*sum(S(2:k-1,3)) + 2*S(k,3); 
    I_W( rows , 1:S(k,2) ) = reshape( C(c_start:c_stop) , S(k,1:2) ); 
 
    % diagonal part 
    c_start = S(1,3) + 3*sum(S(2:k-1,3)) + 2*S(k,3) + 1; 
    c_stop = S(1,3) + 3*sum(S(2:k,3)); 
    I_W( rows , columns ) = reshape( C(c_start:c_stop) , S(k,1:2) ); 
 
end