Dear SPM experts:
I want to run realign by-passing the spm-user interface (for possible
automation). First I use the spm interface (PET/SPECT).
realign
number of subjects: 1
then I selecte the two files (longitudinal studies from one
person)
Coregister & Reslice
Sinc Interpolation
All Images (1...n)
The generated r*img (hdr, mat) files are then renamed as spmr*.img (hdr
mat),
In running above, I find that
flagsC.quality=0.5
flagsC.fwhm = 8
flagsC.rtm =[]
and
FlagsR.hold=-9;
FlagsR.mask=1;
FlagsR.which=2;
FlagsR.mean=0;
then, I just run
spm('pet');
global MODALITY SWD
SWD=spm('Dir');
MODALITY='PET';
%the above codes may be un-necessary
spm_realign(P,flagsC);
spm_reslice(P,FlagsR);
where P is the 1X1 cell containing the two file names
to re-generate the r*img (hdr mat) files.
I expect the spm-interface procedure generated r*img should be identical
to the one generated directly by running spm_realign.m and spm_reslice.m.
What I found however, they are not EXACTLY identical. The maximue pixel
value difference, in most slices, is one (should be zero, if identical)
and in some slice levels, the difference is as high as 10.
Visual examination of the two images could not detect any differences and
pixel-by-pixel linear regression give almost a 45 degree line.
Your help is greatly appreciated!
Kewei
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