% test SVD on real image

clear
clc

I = imread('baboon.bmp');
% I = 128 * ones(256);
I = double(I);

[U, S, V] = svd(I);

% Irec = U * S * V';
Vtranspose = V';
Irec = zeros(256);
myPSNR = [];
mySSIM = [];
for i = 1 : 255
    tempIter = S(i,i) * U(:,i) * Vtranspose(i,:);
    Irec = Irec + tempIter;
    myPSNR(end+1) = psnr(I,Irec,255);
    mySSIM(end+1) = ssim(I,Irec);
    imshow(Irec,[0 255]), xlabel(i)
    if rem(i,5)==0
        drawnow
    end
end

figure,
subplot(1,2,1), imshow(I,[0 255])
subplot(1,2,2), imshow(Irec,[0 255])

figure,
subplot(1,2,1), plot(myPSNR), title('PSNR vs. Iteration'), xlabel('Iteration'), ylabel('PSNR'), grid on
subplot(1,2,2), plot(mySSIM), title('SSIM vs. Iteration'), xlabel('Iteration'), ylabel('SSIM'), grid on

q = inf;