clear all;close all;
I=imread('peppers.TIF');
I=rgb2gray(I);
Idouble=double(I)/256;
imwrite(I,'image_a.jpg','jpg');
H0=1/8*[-1 2 6 2 -1];
H1=1/2*[-1 2 -1];
G0=1/2*[1 2 1];
G1=1/8*[-1 -2 6 -2 -1];
U0=conv2(Idouble,H0,'same');
U1=conv2(Idouble,H1,'same');
V0=U0(:,1:2:size(U0,2));
V1=U1(:,1:2:size(U1,2));
b=[V0,V1];
imshow(b)
imwrite(b,'image_b.jpg','jpg');

U0_1=conv2(b,H0,'same');
U1_1=conv2(b,H1,'same');
c=[U0_1(1:2:size(U0_1,2),:);U1_1(1:2:size(U1_1,2),:)];
imshow(c)
imwrite(c,'image_c.jpg','jpg');

W0=zeros(size(I));
W1=zeros(size(I));
W0(:,1:2:size(I,2))=V0;
W1(:,1:2:size(I,2))=V1;
Y0=conv2(W0,G0,'same');
Y1=conv2(W1,G1,'same');
Y=Y0+Y1;
imshow(Y)
imwrite(Y,'recostruct.jpg','jpg')
errormatrix=(Y-Idouble).^2;
err=mean(mean(errormatrix,1))