[Octave-bug-tracker] [bug #41480] image package :normxcorr2 yields different result from matlab

[Carnë Draug]

Update of bug #41480 (project octave):

                  Status:                    None => Fixed                  
             Open/Closed:                    Open => Closed                 

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Follow-up Comment #7:

I have pushed that change to the image package:

https://sourceforge.net/p/octave/image/ci/e9c18bff13be86a0d067969c2a3dcfc405edb0b2/

I have signed that commit with your name and email. As per the emails we
changed in private, I then made some further modifications to make it work
with N dimensional images and follow Octave coding guidelines, expanded
documentation a bit, and added tests.

https://sourceforge.net/p/octave/image/ci/0ed283edee13a5c562b51521a457d5d996fcf022/

For future reference, there's some machine precision error that creeps in, so
even if the template is within the image, the normalized cross correlation may
not have any 1.


total = 0;
for i=1:100
  a = rand (10);
  c = normxcorr2 (a(5:7,5:7), a);
  if (c(7,7) == 1)
    total++;
  endif
endfor


The condition there will fail around half of the times. However, I asked
someone to test this in Matlab and they're not doing any better than us here.

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