How can i illustrate the fast fourier transform of an image ?

Hello ,

i perfrom Fast Fourier Transform on an image .This is my code:

I_fft=fftshift(fft2(I_new)); 
figure();
imagesc(abs(I_fft));
colormap(gray);
%imshow((I_fft));

I was asked to illustrate the result . The problem is that both imagesc and imshow doesn't give me any good result .

Any thoughts would be valuable.

Answer 1

[Bjorn Gustavsson]

Typically you will have to take the log of the magnitude of the fft-coefficients to get a "nice-looking" illustration. That is due to the fact that the amplitudes typically decreases very rapidly. You should also consider displaying the phase of the fourier-coefficients. For that use:

imagesc(angle(I_fft))

For that type of cyclical data the hsv colormap is better than the standard parula or jet.

HTH