fpho=im2double(sig);
fpho1=im2double(re_re_sig);
g0=255^2;
g1=0;
g2=0;
for i=1:512
    for j=1:512
        g1=g1+(fpho(i,j)-fpho1(i,j))^2;        
    end
end
for i=1:512
    for j=1:512
        g2=g2+fpho(i,j)^2;        
    end
end
MSE=(g1*255*255)/(512*512)
PSNR13=10*log10(g0/MSE)
SNR13=10*log10(g2/g1)