Autocorrelation of power spectrum

Question

Have anyone idea how can I implement autocorrelation of power spectrum of one image? I tried using:

 autocorrel = ifft( | fft(power spectrum) | ^ 2 );

but its not working? Do you have any idea why or some other way?

Answer 1

Autocorrelation in time domain is done via convolution. Function is convoluted with self mirrored around 0. Thus, autocorrel = linear_2d_convolution( S(x,y), S(-x,-y) ), where S denotes power spectrum.