www.pudn.com > SPIHT-matlab.zip > func_SPIHT_Dec.m

function m = func_SPIHT_Dec(in) 
% Matlab implementation of SPIHT (without Arithmatic coding stage) 
% 
% Decoder 
% 
% input:    in : bit stream 
% 
% output:   m : reconstructed image in wavelet domain 
% 
% Jing Tian 
% Contact me : scuteejtian@hotmail.com 
% This program is part of my undergraduate project in GuangZhou, P. R. China. 
% April - July 1999 
 
%-----------   Initialization  ----------------- 
% image size, number of bit plane, wavelet decomposition level should be 
% written as bit stream header. 
m = zeros(in(1,1)); 
n_max = in(1,2); 
level = in(1,3); 
ctr = 4; 
  
%-----------   Initialize LIP, LSP, LIS   ---------------- 
temp = []; 
bandsize = 2.^(log2(in(1,1)) - level + 1); 
temp1 = 1 : bandsize; 
for i = 1 : bandsize 
    temp = [temp; temp1]; 
end 
LIP(:, 1) = temp(:); 
temp = temp'; 
LIP(:, 2) = temp(:); 
 
LIS(:, 1) = LIP(:, 1); 
LIS(:, 2) = LIP(:, 2); 
LIS(:, 3) = zeros(length(LIP(:, 1)), 1); 
pstart = 1; 
pend = bandsize / 2; 
for i = 1 : bandsize / 2 
    LIS(pstart : pend, :) = []; 
    pdel = pend - pstart + 1; 
    pstart = pstart + bandsize - pdel; 
    pend = pend + bandsize - pdel; 
end 
LSP = []; 
 
%-----------   coding   ---------------- 
n = n_max; 
while (ctr <= size(in,2)) 
     
    %Sorting Pass 
    LIPtemp = LIP; temp = 0; 
    for i = 1:size(LIPtemp,1) 
        temp = temp+1; 
        if ctr > size(in,2) 
            return 
        end 
        if in(1,ctr) == 1 
            ctr = ctr + 1; 
            if in(1,ctr) > 0 
                m(LIPtemp(i,1),LIPtemp(i,2)) = 2^n + 2^(n-1);   
            else 
                m(LIPtemp(i,1),LIPtemp(i,2)) = -2^n  - 2^(n-1);  
            end 
            LSP = [LSP; LIPtemp(i,:)]; 
            LIP(temp,:) = []; temp = temp - 1; 
        end 
        ctr = ctr + 1; 
    end 
     
    LIStemp = LIS; temp = 0; i = 1; 
    while ( i <= size(LIStemp,1)) 
        temp = temp + 1; 
        if ctr > size(in,2) 
            return 
        end 
        if LIStemp(i,3) == 0 
            if in(1,ctr) == 1  
                ctr = ctr + 1; 
                x = LIStemp(i,1); y = LIStemp(i,2); 
                 
                if ctr > size(in,2) 
                    return 
                end 
                if in(1,ctr) == 1 
                    LSP = [LSP; 2*x-1 2*y-1]; 
                    ctr = ctr + 1; 
                    if in(1,ctr) == 1 
                        m(2*x-1,2*y-1) = 2^n + 2^(n-1);  
                    else 
                        m(2*x-1,2*y-1) = -2^n  - 2^(n-1);  
                    end 
                    ctr = ctr + 1; 
                else 
                    LIP = [LIP; 2*x-1 2*y-1]; 
                    ctr = ctr + 1; 
                end 
                 
                if ctr > size(in,2) 
                    return 
                end 
                if in(1,ctr) == 1 
                    ctr = ctr + 1; 
                    LSP = [LSP; 2*x-1 2*y]; 
                    if in(1,ctr) == 1; 
                        m(2*x-1,2*y) = 2^n + 2^(n-1);  
                    else 
                        m(2*x-1,2*y) = -2^n  - 2^(n-1);  
                    end 
                    ctr = ctr + 1; 
                else 
                    LIP = [LIP; 2*x-1 2*y]; 
                    ctr = ctr + 1; 
                end 
                 
                if ctr > size(in,2) 
                    return 
                end 
                if in(1,ctr) == 1 
                    ctr = ctr + 1; 
                    LSP = [LSP; 2*x 2*y-1]; 
                    if in(1,ctr) == 1 
                        m(2*x,2*y-1) = 2^n + 2^(n-1);  
                    else 
                        m(2*x,2*y-1) = -2^n  - 2^(n-1); 
                    end 
                    ctr = ctr + 1; 
                else 
                    LIP = [LIP; 2*x 2*y-1]; 
                    ctr = ctr + 1; 
                end 
                 
                if ctr > size(in,2) 
                    return 
                end 
                if in(1,ctr) == 1 
                    ctr = ctr + 1; 
                    LSP = [LSP; 2*x 2*y]; 
                    if in(1,ctr) == 1 
                        m(2*x,2*y) = 2^n + 2^(n-1);  
                    else 
                        m(2*x,2*y) = -2^n  - 2^(n-1);  
                    end 
                    ctr = ctr + 1; 
                else 
                    LIP = [LIP; 2*x 2*y]; 
                    ctr = ctr + 1; 
                end 
                 
                if ((2*(2*x)-1) < size(m) & (2*(2*y)-1) < size(m)) 
                    LIS = [LIS; LIStemp(i,1) LIStemp(i,2) 1]; 
                    LIStemp = [LIStemp; LIStemp(i,1) LIStemp(i,2) 1]; 
                end 
                LIS(temp,:) = []; temp = temp-1; 
                 
            else 
                ctr = ctr + 1; 
            end 
        else 
            if in(1,ctr) == 1 
                x = LIStemp(i,1); y = LIStemp(i,2); 
                LIS = [LIS; 2*x-1 2*y-1 0; 2*x-1 2*y 0; 2*x 2*y-1 0; 2*x 2*y 0]; 
                LIStemp = [LIStemp; 2*x-1 2*y-1 0; 2*x-1 2*y 0; 2*x 2*y-1 0; 2*x 2*y 0]; 
                LIS(temp,:) = []; temp = temp - 1; 
            end 
            ctr = ctr + 1; 
        end 
        i = i+1; 
    end 
     
    % Refinement Pass 
    temp = 1; 
    value = m(LSP(temp,1), LSP(temp,2)); 
    while (abs(value) >= 2^(n+1) & (temp <= size(LSP,1))) 
        if ctr > size(in,2) 
            return 
        end 
 
        value = value + ((-1)^(in(1,ctr) + 1)) * (2^(n-1))*sign(m(LSP(temp,1),LSP(temp,2)));  
        m(LSP(temp,1),LSP(temp,2)) = value; 
        ctr = ctr + 1; 
        temp = temp + 1;     
        if temp <= size(LSP,1) 
            value = m(LSP(temp,1),LSP(temp,2)); 
        end 
    end 
     
    n = n-1; 
end