Using MatLab to calculate signal:noise ratio

Question

How do you use MatLab to calculate the SNR?

Update

I only have one file, not two like in the example and it's a .tif.

Answer 1

First Google result for Matlab SNR. Copied from there, in dB:

snr = 10*log10(sum(clean.^2) ./ sum(noise.^2))

EDIT: The signal-to-noise ratio cannot be computed without knowing the signal power and noise power. With only knowledge of the observed (i.e., received) signal, one can blindly estimate the SNR, but this is an open research topic. See "blind quality measurement".