Hi - I'm not sure why you're using "-1" for the brightness threshold? This should be a positive number "greater than noise level and less than contrast of edges to be preserved".
Cheers.
> On 27 Mar 2017, at 01:55, free_learner <[log in to unmask]> wrote:
>
> Hi, that's really strange, for I find that the less-blurring effects are also observed in brain regions , such as white matter/CSF.
>
> I use the following commands to compare the smoothing effects between SUSAN and Gaussian standard smoothing (assuming the standard deviation is 3 mm):
> (1) SUSAN: susan rest4D -1 3 3 1 0 rest_smooth_v1
> (2) Standard: fslmaths rest4D -s 3 rest_smooth_v2 ( fslmaths rest4D -kernel gauss 3 -fmean rest_smooth_v3 )
>
> Maybe I use the commands or options wrongly? Thank you for any suggestions.
>
> At 2017-03-26 16:30:13, "Stephen Smith" <[log in to unmask]> wrote:
> Hi - IIRC SUSAN is used with an "intensity threshold" setting that aims to just distinguish brain from non-brain voxels, to avoid blurring across the brain edge when smoothing. Hence *within* the brain it should be acting almost identically to an equivalent Gaussian standard smoothing.
>
> Cheers.
>
>
>
>> On 25 Mar 2017, at 13:12, huyang <[log in to unmask]> wrote:
>>
>> Dear experts,
>>
>> I find that susan is used for spatial smoothing in Feat/Melodic GUIs and I also notice that the susan's result is much less blurring than that of simple mean filtering (for example, fslmaths input -s sigma output). Therefore, spatial smoothing using susan can be less likely to mix signals from brain regions with different functions, as susan only averages nearby voxels with similar intensity. I would like to confirm whether my understanding above is correct? In addtion, are there any rigorous comparisons between susan and simple mean filtering? How much improvements can be made by susan in fMRI senario?
>>
>> Many thanks,
>>
>> Yang Hu
>
>
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> Stephen M. Smith, Professor of Biomedical Engineering
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> FMRIB, JR Hospital, Headington, Oxford OX3 9DU, UK
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Stephen M. Smith, Professor of Biomedical Engineering
Head of Analysis, Oxford University FMRIB Centre
FMRIB, JR Hospital, Headington, Oxford OX3 9DU, UK
+44 (0) 1865 222726 (fax 222717)
[log in to unmask] http://www.fmrib.ox.ac.uk/~steve
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Stop the cultural destruction of Tibet
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