function filtered_photo = fft_filter(photo, radius)
% fft_filter.m
% FFT filter
% filtered_photo = fft_filter(photo, radius)
% hipass-filters the given photo with a circular
% mask in the frequency domain of the given radius.
% 1999-02-28:DAV: David Cary <d.cary at ieee.org> started.


figure
image(photo)
zoom on
colormap(gray(256))
title('original')
drawnow


offt = fft2(photo);
figure
imagesc(log(abs(fftshift(offt))+1) )
zoom on
colormap(gray(256))
title('fft2(original)')
drawnow

mask_part = circle(2*radius+1);
mask = zeros(size(photo));
y = -radius:radius;
x = -radius:radius;
[height,width] = size(photo);
mask(floor(height/2) + y, floor(width/2) + x) = mask_part;
mask = 1 - mask;

figure
cutout = fftshift(mask) .* offt;
imagesc(log(abs(fftshift(cutout))+1) )
colormap(gray(256))
drawnow

figure
filtered_photo = abs( ifft2(cutout) );
imagesc(filtered_photo)
colormap(gray(256))
drawnow




% end fft_filter.m