Can anyone tell me what that first (new) phase of realigning is doing
in spm99? It says something like 'eliminating unnecessary voxels' and
then presents a graph with iterations and 'fractional quality loss' as
axes (apparently reversed). I got a little worried when at the 8th
iteration the 'quality' axis was at 0.5 -- does this mean it's done
something like degraded the 'quality' of the image to 50%? Is that a
good thing?
Also, for PET data, 99 is apparently being clever and doing the realigning
twice (ie to the mean) but I must not understand the graphical display
of the movement params then as they always appear to be null values for
the first scan. Is the first scan not being realigned to the mean or
is this not being displayed for some reason?
Thanks much!
- Joe
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Joseph Devlin, PhD * email: [log in to unmask]
Center for Speech and Language * [log in to unmask]
Experimental Psychology Department *
University of Cambridge * Phone: 01223 766 454
Cambridge, CB2 3EB * Fax: 01223 766 452
England *
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