A comment on "A novel approach for the registration of weak affine images"
In the recent paper (Li and Zhang, 2012) a mapping model of weak affine transform (WAT) was proposed for registering images of flat scenes. We show that such a model may cause inaccuracies when registering images with non-uniform scaling differences, even if they seemingly behave according to this model. Mathematical reason of this is that WAT is neither invertible nor closed. We explain why mapping models forming a group should be preferably used for registration and show some examples of models belonging to affine subgroups. (c) 2013 Elsevier B.V. All rights reserved.
weak affine transform affine transform affine subgroups image registration area-preserving affine transform