correlation in Matlab

function g = dftcorr(f,w)
[M, N] = size(f);
f = fft2(f);
w = conj(fft2(w, M, N));
g = real(ifft2(w.*f));

run:

g = drtcorr(f, w);
[I, J] = find(g == max(g(:)))