[Insight-users] demons deformable filter

[Corinne Mattmann]

Hi,

I am using the demons deformable filter but as I have images with just
one "material" - therefore basically black-white-images with smoothed
transitions - the registration is not perfect. In fact, the quality of
the registration depends on the similarity of the two initial images.
That's why I would like to try another demons-formula taken out of
Jean-Philippe Thirion's paper "Fast Non-Rigid Matching of 3D Medical
Images" (formula 5). For that formula you need to calculate the gradient
of the reconstructed moving image at each iteration.
Can you tell me how I can get to this gradient in the function
ComputeUpdate(...) in itkDemonsRegistrationFunction.txx?

Thanks very much,
Corinne