%% dft2demo2
%% show image and log of shifted |DFT|

% get image
load chess
% get 2D FFT of image
X= X-mean(mean(X)); % get rid of the DC component
X = zeros(126); X(21:40,21:40)=1;
FX = fft2(X); 
sFX = fftshift(FX);

% display results 
figure(1)
showgimg(X,128)
title('original image');

figure(2)
[m,n]=size(X);
% showgimg((1+abs(sFX)),128,[],[-n/2,n/2],[-m/2,m/2])
showgimg(log(.01+abs(sFX)),128,[],[-n/2,n/2],[-m/2,m/2])

%title('log(1+|dft|)');
title('shifted log(1+|dft|)');