function p = psnr(x,y)

% psnr - compute the Peack Signal to Noise Ratio, defined by :
%       PSNR(x,y) = 10*log10( max(max(x),max(y))^2 / |x-y|^2 ).
%
%   p = psnr(x,y);
%

d = mean( mean( (x(:)-y(:)).^2 ) );
m1 = max( abs(x(:)) );
m2 = max( abs(y(:)) );
m = m1;

p = 10*log10( m^2/d );