encode_main.m

晓波压缩编码源程序及相关文档好东西

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%%%%%%%%%%%%%%%%%%              encode             %%%%%%%%%%%%%%%%%%%
%%%%%%%%%%%%%%%%%%           by   zzf               %%%%%%%%%%%%%%%%%%%
%%%%%%%%%%%%%%%%%%%     started  on  11.6 2006      %%%%%%%%%%%%%%%%%%%
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% function  encode

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% INPUT u0 = original image
% OUTPUT: dwt image and rec image
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clear all;
close all;


%%%%%%%%%%%%%%%%%%   original  image    %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

%the beginning
% read the original data u0 in BMP format

u0=imread('Lena.bmp');
u0=double (u0);
% cut a piece, convert to double
u0=double(u0); [M0 N0]=size(u0);
% visualize the image u0 in Matlab (rescaled)
figure(1); subplot(1,2,1); 
imagesc(u0); axis image;
title('original data');
% image(u0)
% axis off;
colormap(gray);

%%%%%%%%%%%%%%%%%%%%%%%     wavedec         %%%%%%%%%%%%%%%%%%%%%%%%%%%%%
[a1,h1,v1,d1]=dwt2(u0,'bior3.7');
[a2,h2,v2,d2]=dwt2(a1,'bior3.7');

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%   parameter  
%---max   max of u0(i,j)
%---min    min of u0(i,j)
%---delta   
%---step    number of different values
%---step_i  
 [M N]=size(a2)
max=0;min=256;
step=170;
for i=1:M
    for j=i:N
        if a2(i,j)>max
            max=a2(i,j);
        end
        if a2(i,j)<min
             min=a2(i,j);
         end
     end
 end
 
 delta=(max-0.1-min)/(step-1);
            
 %------------------------probility-------------------------------
 
 pro=zeros(1,step);
 data_table=zeros(1,M*N);
 data_k=0;
 for i=1:M
    for j=1:N
        data_k=data_k+1;
        step_i=round((a2(i,j)-min)/delta)+1;
        a2(i,j)=min+(step_i-1)*delta+delta/2;
        pro(step_i)=pro(step_i)+1/(M*N);
        data_table(1,data_k)=step_i;
    end
 end
 
 
  %--------------------------  rate  -----------------------------
  
  h=0;
  for i=1:step
      if pro(i)~=0
         h=h-pro(i)*log2(pro(i))
      end   
  end
  rate=8*M0*N0/h/(M*N)
  

 %%%%%%%%%%%%%%%%%%       huffman end encode    %%%%%%%%%%%%%%%%%%%%%%%%%%%%
 
  huff_table=HuffmanTree(pro);
  code_table=encode(huff_table);
  for i=1:(M*N)
      if i==1
          code_out=code_table(1,:);
      else
          p=data_table(1,i);
         code_out=strvcat(code_out,code_table(p,:))
     end
 end
 
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 
 
  %%%%%%%%%%%%%%%%%%     decode   and rec   %%%%%%%%%%%%%%%%%%%%%%%%%%%%
 
%    A3=zeros(75,75);
 for i=1:M*N
     code=deblank(code_out(i,:));
      step_i=strmatch(code,code_table);
     data_table(1,i)=min+(step_i-1)*delta+delta/2;
 end
 
 
 for i=1:M
     k=((i-1)*N+1);
     a2(i,:)=data_table(1,k:(k+N-1));
 end
 a1=idwt2(a2,[],[],[],'bior3.7');
%  A3=wkeep(A4,[135 135]);
 u=idwt2(a1,[],[],[],'bior3.7');
 subplot(1,2,2);
 imagesc(u); axis image;
 title('rec picture');
% image(u0)
% axis off;
colormap(gray);
 
%%%%%%%%%%%%%%%%%%     psnr            %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

 %-----------------------  psnr--------------------------------------------------
 sum=0;
 for i=1:M0
     for j=1:N0
         k=u0(i,j)-u(i,j);
         sum=sum+k^2;
     end
 end
 sum=sum/(M0*N0);
 sum=255*255/sum;
 PSNR=10*log10(sum)

 
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%%%%%%%%%%%%%%%%              encode             %%%%%%%%%%%%%%%%%%%
%%%%%%%%%%%%%%%%%%           by   zzf               %%%%%%%%%%%%%%%%%%%
%%%%%%%%%%%%%%%%%%%     started  on  11.9 2006      %%%%%%%%%%%%%%%%%%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%