Image 2D Real Cepstrum with DFT, Is `ifftshift` Needed?
If you have image in the spatial domain, in order to calculate its DFT transform you should use fft.
Once you have its DFT in order to get back to the spatial domain use the function ifft.  

Either way, the DFT transform gives you the data in the [0, 2pi] axis.
Use fftshift to move it into the [-pi, pi] domain as seen in the paper.

Good Luck.

MATLAB Code

This code worked for me:

mInputImage = imread('3.png');
mInputImage = double(mInputImage) / 255;
mInputImage = mean(mInputImage, 3);

mImageDft = (fft2(mInputImage));

mImageDft = log(1 + abs(mImageDft));

mImageCepstrum = abs(fftshift(ifft2(mImageDft)));

mImageCepstrum = mImageCepstrum / max(mImageCepstrum(:));

figure();
imshow(mImageCepstrum);


Enjoy...