www.pudn.com > SPIHT_bandelet.rar > psnr.m

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); 
% 
%   Copyright (c) 2004 Gabriel Peyré 
 
d = mean( mean( (x(:)-y(:)).^2 ) ); 
m1 = max( abs(x(:)) ); 
m2 = max( abs(y(:)) ); 
m = max(m1,m2); 
 
p = 10*log10( m^2/d );