Posts Tagged ‘global optimization’

Image registration with genetic algorithms, again


Given two images, we want to “reigster” them.

After resizing (pyramid, to speed-up the algorithm) and normalizing (to improve the registration) I’ve tried to find shift + rotation (3 degrees of freedom) using algorithms in matlab’s global optimization toolbox.

  • genetic-algorithm – results are good only if initial guess is good/ image offset is small, even with customized parameters.
  • Direct Search – very good results (but the offset is integer, for some reason)
  • Simulated Annealing – poor results

In all cases, the following function was used:

%try to make B similar to A
function a = cor(alfa1)
 global A B 
 global roi

 b1=imChange(B, alfa1);
 a1=imcrop(A, roi);
 a = 1-corr2(a1,b1);

%vector of form [offset-x, offset-y, angle]
function out = imChange(im, vector)
 global roi
 alfa = vector(3);
 offset = vector(1:2);
 B1=imrotate(im, alfa,'bicubic', 'crop');
 out=imcrop(B1, roi+[offset 0 0]);