[Nexus] Float imaging data in NXtomo and NXtomoproc

[Sam Tygier - STFC UKRI]

Hello,

I am working on Mantid Imaging which features reading and writing of neutron imaging data from NXtomo and NXtomoproc.

While the data from the instrument usually arrives as uint16 we do our processing in, and reconstruct to float32. The NXtomo and NXtomoproc definitions both specify the data array as NX_INT. Ideally, we'd like to be able to store our datasets in float32, both for reconstructed output and intermediate processed projections. We do this with TIFFs and it avoids any loss of precision.

Is it ok to store float32 in these arrays? I assume this is bad because the files would not be valid and other software may not be able to correctly open them.

Could the definitions be updated to use NX_NUMBER? What's the best way to propose this change?

The NXtomoproc data array has attributes 'transform', 'offset', 'scaling'. Are these to specify int-float conversion? Is there any documentation? Could these be added to NXtomo?

Thanks,
Sam

​​Dr Sam Tygier​​
Senior Scientific​ Software Engineer
Science and Technology Facilities Council
sam.tygier at stfc.ac.uk​​