segcmp_bior68a33.m

image compression matlab code

%removes all variables from the workspace. 
clear;
clear all;
close all;

%start clock for calculate time need to execute this algorithm
t=cputime; 

%read the input image
input_ima=imread('saturn.tif');

%Discrete wavelet transform is used to seperate the input as 
%low frequency and high frequency component
[lowfreq_comp,highfreq_compH,highfreq_compV,highfreq_compD] = DWT2(input_ima,'bior2.2');


app_ima=uint8(lowfreq_comp);
%to chow low frequency component 
% figure;
% imshow(app_ima);

deta_ima=imadd(highfreq_compH,highfreq_compV);
detail_ima=imadd(deta_ima,highfreq_compD);
% figure;
% imshow(detail_ima);
CH1=uint8(detail_ima);
out=imadd(app_ima,CH1);
% figure;
% imshow(out); 

Nl=1;Nh=2;
[Cl,Sl] = WAVEDEC2(lowfreq_comp,Nl,'bior6.8');
[Ch,Sh] = WAVEDEC2(CH1,Nh,'bior3.3');
THR=20;
 [XCl,CXCl,LXCl,PERF0l,PERFL2l] = WDENCMP('gbl',Cl,Sl,'bior6.8',Nl,THR,'s',1);
  [XCh,CXCh,LXCh,PERF0h,PERFL2h] =  WDENCMP('gbl',Ch,Sh,'bior3.3',Nh,THR,'s',1);
   X = WAVEREC2(CXCl,LXCl,'bior6.8');
    Y = WAVEREC2(CXCh,LXCh,'bior3.3');
    z = IDWT2(X,Y,Y,Y,'bior2.2')
    %z=imadd(X,Y);
    recons_ima=uint8(z);
    out=imresize(recons_ima,[328,438]);
    figure;
    imshow(out);
    title('Recons ima using SBWC')
    
input_ima1=double(input_ima);
    out1=double(out);
    error=0;
  for y=1:438
     for x=1:328
        MSE=((input_ima1(x,y))-(out1(x,y)))^2;
        error=MSE+error;
      %  error_sbw1=error_sbw+MSE2;
     end
 end
 MSE_WO=((1/(328*438))*error);
 disp(MSE_WO);
 %MSE_SBW=(1/(256*256))*error_sbw1;
    
 disp('PSNR value for decompressed image using segmentation based wavelet compression');
 PSNR_WO=20*log10(255/sqrt(MSE_WO));
 disp(PSNR_WO);
 diff_ima=imsubtract(input_ima1,out1);
figure;
imshow(diff_ima);
title('difference image in SBWC');
disp('the time need to execute this SBWC'); 
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);
disp(PERF0l);
    disp(PERF0h);
    cr=((PERF0l+PERF0h)/2);
    disp(cr);
    
%     
% PSNR value for decompressed image using segmentation based wavelet compression
%    39.0281
% 
% the time need to execute this SBWC
% 
% ans =
% 
%    11.3700
% 
%   8.9682e+003
% 
% signal to noise ratio
%    30.4243
% 
% 
%    88.1242