[Insight-developers] query/suggestion: adjustable tolerance in ImageToImageFilter

[Richard Beare]

Hi,
I thought I'd mention a problem I just came across that may have a fix
I missed. If not then perhaps it can go into a feature request.

I was performing a mask operation and received an error saying that
images weren't in the same space. The relevant code is in the
ImageToImage filter base class where the orientation matrices are
checked. There doesn't seem to be a way of adjusting the tolerance or
turning this check off. My problem image was produced by the spm8
coregistration procedure, and the difference in orientation matrix
introduced by rounding  (I assume) was only just greater than the hard
coded tolerance. I've fixed the problem by explicitly copying the
geometry in the input nifti files using the fslcpgeom tool, but I
suspect there should be some ITK specific option to deal with this
inside a filter. Obviously image information can be copied inside ITK
code too. Not sure if there is a "right" way to deal with this issue.