normxcorrn_fg

PURPOSE ^

Normalized n-dimensional cross-correlation with a mask.

SYNOPSIS ^

function C = normxcorrn_fg( T, T_fg, A, shape )

DESCRIPTION ^

 Normalized n-dimensional cross-correlation with a mask.

 Similar to normxcorrn, except takes an additional argument that specifies a figure
 ground mask for the T.  That is T_fg must be of the same dimensions as T, with each
 entry being 0 or 1, where zero specifies regions to ignore (the ground) and 1 specifies
 interesting regions (the figure).  Essentially T_fg specifies regions in T that are
 interesting and should be taken into account when doing normalized cross correlation.
 This allows for templates of arbitrary shape, and not just squares.  

 Note: this function is approximately 3 times slower then normxcorr2 because it cannot
 use the trick of precomputing sums.

 INPUTS
   T    - template to correlate to each window in A
   T_fg - figure/ground mask for the template
   A           - matrix to correlate template to
   shape       - [optional] 'valid', 'full', or 'same', see convn_fast help

 OUTPUTS
   C           - correlation matrix

 EXAMPLE
   A=rand(50);  B=rand(11);  Bfg=ones(11);
   C1=normxcorrn_fg(B,Bfg,A);  C2=normxcorr2(B,A);     
   figure(1); im(C1); figure(2); im(C2); 
   figure(3); im(abs(C1-C2));

 DATESTAMP
   29-Sep-2005  2:00pm

 See also NORMXCORRN

CROSS-REFERENCE INFORMATION ^

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