Radial averaged power dispersion vs frequency of an image

I am totally biginner of Matlab. now I want to do the FFT of an image and plot 1D Radial averaged power dispersion vs frequency of the image, How can do it?

[KSSV]

Read about fft2.

[Bjorn Gustavsson]

Then about the "central slice theorem" and the radontransform. This wikipedia-page on the Projection-slice_theorem should be enough.

HTH