xcorr2

% C = xcorr2 (A, B)
%    Compute the 2D cross-correlation of matrices A and B.
% C = xcorr2 (A)
%      Compute two-dimensional autocorrelation of matrix A.
% C = xcorr2 (..., 'scale')
%      biased   - scales the raw cross-correlation by the maximum number
%                 of elements of A and B involved in the generation of 
%                 any element of C
%      unbiased - scales the raw correlation by dividing each element 
%                 in the cross-correlation matrix by the number of
%                 products A and B used to generate that element 
%      coeff    - normalizes the sequence so that the largest 
%                 cross-correlation element is identically 1.0.
%      none     - no scaling (this is the default).