Hi,
There is a quantization in the partial volume estimation
code which is probably driving this. I would not be
worried about it as the quantization level is well below
the noise floor in the estimation of the partial volume values.
All the best,
Mark
On 19 Oct 2010, at 16:17, Aaron Alexander-Bloch wrote:
> Dear FSL list,
>
> When I run FAST on my structural scans, and look at the gray matter
> probability values for each voxel, I typically get small numbers of
> "ties" in the probability values that I wouldn't have expected. I'm
> sure it's not a problem, but I'd like to understand why this happens.
>
> For example if I look at a small region, composed of 962 ~1mm^3 voxels
> all with gray matter probabilities greater than .8, 3 probability
> values are repeated twice: 0.899646 0.901879 0.869251. I'm surprised
> the algorithm outputs ties at that degree of precision.
>
> Sorry if this question doesn't make sense. I'd be happy to clarify
> further.
>
> Best
> Aaron
>
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