Hi Matthew,
Maybe I'm not planning on using fslcc in the manner for which it was
intended, but doesn't that mean that the resulting correlations will be
dependent on somewhat arbitrary things such as the number of 0 voxels?
i.e., the size of a brain mask that was previously applied?
Also, to avoid anyone getting confused, I'm sure you meant to include a
sqrt factor in your denominator, right? :)
thanks,
-MH
On Tue, 2011-11-01 at 13:53 +0000, Matthew Webster wrote:
> Hello Michael,
> No voxels are explicitly excluded from the calculation. The
> two input images are ( depending on command line options )
> demeaned and then all timepoints and voxels are looped
> across to generate
>
> (image1_timepoint1*image2_timepoint2)/(sumsquares(image1_timepoint1).sumsquares(image1_timepoint2))
>
> Hope this helps
>
> Matthew
> >
> >> Hello,
> >> I want to compute to the correlation (across voxels) of two images, and
> >> my understanding is that's what 'fslcc' is for. But, it isn't obvious
> >> to me what determines which specific voxels go into that calculation.
> >> If a voxel is zero in EITHER input volume, is that voxel then excluded
> >> from the calculation? (in which case I can control the voxels that
> >> contribute to the calculation by thresholding my input appropriately
> >> beforehand?)
> >>
> >> thanks,
> >> -MH
> >>
> >>
> >
> >
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