function d=db(I,In)
%% private function: by Guy Gilboa
%% computes SNR in dB's
%% input I - original signal, In - noisy signal
%% example: snr=db(I,In);

n=I-In; % noise
Ps = sum(sum((I - mean(mean(I))).^2)); % signal power (no DC)
Pn = sum(sum(n.^2)); % noise power (assuming no DC)

d=10*log10(Ps/Pn);