Hi,
if you run melodic by commnad line and didn't smooth your data as aprt of some preprocessing, it will not be smoothed spatially.
Cheers-
Andreas
________________________________________
Von: FSL - FMRIB's Software Library [[log in to unmask]] im Auftrag von Srinivas [[log in to unmask]]
Gesendet: Dienstag, 1. Dezember 2009 22:22
An: [log in to unmask]
Betreff: Re: [FSL] Melodic
Hi Christian,
Thanks for your reply. Is there a way to turn off the smoothing option from
the command line (melodic) rather than using GUI?
Srinivas
On Tue, 1 Dec 2009 21:06:36 +0000, Christian F. Beckmann
<[log in to unmask]> wrote:
>Hi
>
>By default, melodic removes the each voxels' mean value over time, i.e.
removes the mean image - so the data is zero centred. The degree of spatial
smoothness is controlled for in the pre-proc tab in the GUI - if you set this to
0 then no additional spatial smoothing will be done. There is no temporal
smoothing. Melodic will estimate the data smoothness in order to get a more
accurate estimation of the number of underlying components. And no, the first
set of estimates are not saved.
>cheers
>Christian
>
>
>
>On 30 Nov 2009, at 21:18, Srinivas wrote:
>
>> Hi all,
>>
>> I have questions in the pre-processing and PPCA stages?
>>
>> 1. Data - Is the mean removed per image or per voxel before doing PPCA? I
>> see that "Estimating data smoothness" message appears before doing PCA.
>> What kind of smoothing is done (Spatial or temporal)? Is there a way to
turn
>> off that option.
>>
>> 2. PPCA - Only PCA results in the 2nd reduction stage are saved. Is there
a
>> way to get the PCA information (whitening) in the first data reduction
stage of
>> the temporal concatenation method?
>>
>> Thanks for the great software.
>>
>> Rnsk. Srinivas
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