Anyone have an idea of how I can implement autocorrelation of power spectrum of one image? I tried using:
autocorrel = ifft( | fft(power spectrum) | ^ 2 );
but it's not working. Do you have any idea why or some other way?
Signal Processing Stack Exchange is a question and answer site for practitioners of the art and science of signal, image and video processing. It only takes a minute to sign up.
Sign up to join this communityAnyone have an idea of how I can implement autocorrelation of power spectrum of one image? I tried using:
autocorrel = ifft( | fft(power spectrum) | ^ 2 );
but it's not working. Do you have any idea why or some other way?
The autocorrelation function is the inverse Fourier Transform of the power spectrum. I have no idea where you got your formula from or what your calculation is meant to be doing. Are you sure that you are reading the book/journal article/application note/website/Wikipedia or whatever correctly?
In any case, if you want to compute an autocorrelation
as an ifft
, you should be careful about making sure that
the power spectrum vector is set up right. If the
autocorrelation function that you compute as the iffy
does not have a peak at the origin (or as the first
entry in the vector for MATLABi folks) and have the
symmetry property $R[i] = R[-i]$ in real life and
the appropriately translated version in MATLAB, something
is awry.