Image processing (2D FFT)

okay so here is the problem i have and i cant find a proper solution to.

We have a school project to do and we decided that we would do it in Matlab

the problem is: We should do a 2D fft of photo, then we have to use only 1/3 of values to draw the picture and we should draw a original photo and next to it the approximation of that photo using fourier basis

I have never done anything like this, we played a bit with fourier transform in school but my knowledge is not enough to solve this type of problem

and our teacher is like if we ask something most likely she would say that we should use internet to find the solution so here i am trying my luck :D

[Image Analyst]

So you want to throw away

1. 2/3 of the spatial domain image and redraw, or
2. 2/3 of the FT image, reconstruct, and redraw?

Which 2/3 of the spatial or FT image do you want to throw away? Just randomly select pixels? Just throw away the outer 2/3 of the FT image, which essentially does a low pass filter?

[Vincent Sin]

2/3 of the FT image

[Image Analyst]

Easy. Use fft2() then use indexing to erase bands of the image like

ftImage = fftshift(fft2(grayImage));
ftImage(row1:row2, :) = 0;

Set all four border bands to zero then call fftshift() again followed by ifft2(). Show your work below.