[Insight-developers] Suggestion: Tensors and Tensor Image Filters

[Torsten Rohlfing]

Greetings!

It appears that there is not much functionality in ITK currently for 
processing (MR diffusion) tensor data. I am therefore currently in the 
process of writing such components myself.

Since I am planning to contribute the resulting code to ITK (if there is 
interest), I wanted to ask for comments on some design decisions before 
getting too far into the endeavour. Of course I would also be very 
interest to hear whether this work has been done already (or is in 
progress somewhere) and my efforts are, therefore, futile.

Most fundamentally in terms of design, I am unsure whether the basic 
tensor processing operations (e.g., eigenvalues, eigenvectors, 
potentially common anisotropy measures) should be implemented entirely 
in image filter classes for tensor images (similar to the vector 
gradient magnitude filters for example). It seems to me that a separate 
tensor class would make sense to provide access to basic functions such 
as eigensystem decomposition, which is useful for many tensor 
operations, whereas the anisotropy measures for example should probably 
go into filter classes.

Also, can anyone think of a reason why the tensor dimension (i.e., the 
tensor matrix size) should be a template parameter (as opposed to fixed 
3x3)? My current state of mind is that tensor image dimensions should 
definitely be templated to allow processing of 2D slices, whereas the 
tensors themselves really don't seem to make much sense in anything 
other than 3D.

Looking foward to comments and suggestions.

Best,
  Torsten