function  [psnr] = PSNR (A,B)
%
%function  [psnr] = psnr (A,B)
%
%
   mse  = mserror(A,B)                   % MMSE
   if (mse == 0)
     psnr=Inf;
   else
     psnr = 10*log10(255^2/mse);          % PSNR
   end