Dear Jesper,
Many thanks for your helpful response (as always)!
Best wishes,
Hamied
-----Original Message-----
From: FSL - FMRIB's Software Library [mailto:[log in to unmask]] On Behalf Of Jesper Andersson
Sent: 28 September 2017 10:23
To: [log in to unmask]
Subject: Re: [FSL] Negative values from Eddy
Dear Hamied,
>
> Please could you explain how FSL's FDT tools (DTI-FIT, etc) deal with negative voxel values from Eddy? I would really appreciate any hints.
the negative values are a consequence of the negative sidelobes of the interpolation kernel (even though spline interpolation doesn’t use an interpolation kernel as such, one can work out what the corresponding kernel should look like).
I think most/all FSL tools will now handle the “gracefully” by simply replacing them by zero (or something very close to zero). If you want to use non-FSL tools after eddy/topup you can always use fslmaths to replace the negative values in that same fashion.
Jesper
>
> I look forward to hearing from you.
>
> Many thanks.
>
> Best wishes,
>
> Hamied
>
> Dr Hamied A Haroon
> The University of Manchester
>
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