function q = dummy(a,b)

% motion from fft
% fast conv; see how much image is shifted over
% motion_estimation by fft methods: cross spectrum, CROSS SPECTRUM

A = fft(a);
B = fft(b);
BA = conj(B).*A;       % conj is like reversal in time domain
% ifft(conj(fft([1,2,3,4]))) = [1,4,3,2]
Q = BA(:)./sqrt(A(:).*conj(A(:)).*B(:).*conj(B(:)));
q = ifft(Q);

%clg
%hold off
%subplot(211)
%plot(real(q))
%title('RE of cross/sqrt(pwrA pwrB)')
%plot(real(ifft(BA)))
%title('cross')

