Circular Cross Correlation 2D Using FFT

Hello,

How to do Circular Cross Correlation In 2D Using fft ?

I checked this code for vectors and it seems that it works.

Z=ifft2(fft2(X1).*conj(fft2(X2)));

Is this code works also for matrix ?

Dims:

X1 : [m,n]

X2: [m,n]

Z: [m,n]

Thank You.

Answer 1

[David Goodmanson]

Hi Ziv,

yes, it works similarly.

m = 5;
n = 6;
q = 4;
A = randi(m,n,q);
B = randi(m,n,q);
C = zeros(size(A));
for j = 1:n
    for k = 1:q 
        C(j,k) = sum(circshift(A,[1,1]).*circshift(B,[j,k]),'all');  % [1 1] adjusts the indexing
    end
end
C

ifft2(fft2(A).*conj(fft2(B)))  % agrees with C