DFT and FFT of Image

Shift the Fourier transform so that it is centered around the middle of your figure and plot the absolute value of the shifted DFT. Then apply the log transform (log(1 + DFT)) and plot your result.

I know that I'm supposed to use fft2 and fftshift. I have the image and this is the code I have this far.

>> X = imread('granular_media.jpg');

>> X1 = double(X(501:700,1401:1600));

>> X2 = double(X(1:200,1:200));

I need to first compute the DFT of the 200x200 subimages that I created. Any help with this?

[JANITHA]

DFT in image processing log of magnitude of FT