How to view the Frequency content of an image

I want to view the frequency content of an image. For that I perform FAST FOURIER TRANFORM for my image.

I was unable to plot the output of fft function with respect to frequency .

I need to find the region of frequency where the energy of an image is located or frequency content of an image.

Answer 1

[Bjorn Gustavsson]

Try something like:

ftI = fft2(I);
imagesc(log10(abs(ftI)))
caxis([-6 0]+max(caxis))

Then you have the DC-component in the upper left corner, to shift that to the centre use fftshift.

HTH