%IMAGE COMPRESSION USING WAVELET TRANSFORM
clear all;
close all;
t=cputime; 
input_ima=imread('saturn.tif');

N=5;
[CA,CH,CV,CD] = DWT2(input_ima,'db2');
[C,S] = WAVEDEC2(CA,N,'db2');
THR=20;
 [XC,CXC,LXC,PERF0,PERFL2] = WDENCMP('gbl',C,S,'db2',N,THR,'s',1);
    X = WAVEREC2(CXC,LXC,'db2');
    z = IDWT2(X,CH,CV,CD,'db2')
    out=uint8(z);
    out1=imresize(out,[328,438]);
     disp('The compression ratio using WBC');

disp(PERF0);    
figure;
    imshow(out1);
    title('recons ima using wbc only');
    
input_ima1=double(input_ima);
    out2=double(out1);
    error=0;
  for y=1:438
     for x=1:328
        MSE=((input_ima1(x,y))-(out2(x,y)))^2;
        error=MSE+error;
      %  error_sbw1=error_sbw+MSE2;
     end
 end
 MSE_WO=(1/(328*438))*error;
 %MSE_SBW=(1/(256*256))*error_sbw1;
    
 disp('PSNR value for decompression image using wavelet compression only');
 PSNR_WO=20*log10(255/sqrt(MSE_WO));
 disp(PSNR_WO);
 
 diff_ima=imsubtract(input_ima1,out2);
figure;
imshow(diff_ima);
title('difference image');
disp('the time need to execute this WBC only'); 
cputime-t
in=imresize(input_ima1,[1,143664]);

va=var(in);
disp(va);
snr=10*log10(va/MSE_WO);
disp('signal to noise ratio');
disp(snr);

% The compression ratio using WBC
%    90.3647
% 
% PSNR value for decompression image using wavelet compression only
%    36.7295
% 
% the time need to execute this WBC only
% 
% ans =
% 
%     9.7300
% 
%   8.9682e+003
% 
% signal to noise ratio
%    28.1257