Hello,
I think my message got scrubbed from my last post with the pictures.
I ran mris_preproc on 56 subjects and then graphed the
concatenated image. I also read this image into matlab and did the
averaging using matlab, and then graphed the resulting image. When I
did this, the two average pictures were slightly different. I thought
that mris_preproc just simply averages all the subjects into common
space. I noticed that its vector in matlab keeps the thickness value
for all vertex's for all 56 subjects. I want to have the matlab
capability for some custom processing I am doing, but the discrepancy
leads me to think that mris_preproc is not a simple average. Can
anyone elucidate this for me? Thank you!
Matlab script. Only
place I would suspect a wrong assumption is when I throw out the rest
of the subjects at curv4=curv3(1,:,:,1)
%Select your input thickness file
path='/mnt/users/Jeff/fs/lc/HIV/pass2pics/416/diff/nc.rh.ave.mgh';
%Read the thickness file
curv=MRIread(path);
%Select the volume attribute
curv2=curv.vol;
%Create a duplicate thickness array for manipulation
curv3=curv2;
%Get the number of concatanated subjects
tmp=size(curv2);
m=tmp(4)
clear 'tmp'
%Sum each vertex for all your subjects
for im=2:m
for in=1:7
curv3(1,:,in,1)=curv3(1,:,in,1)+curv2(1,:,in,im);
end
end
%Select just the first frame
curv4=curv3(1,:,:,1);
%Compute the average thickness
curv.vol=curv4/m;
%Write to thickness file
MRIwrite(curv,'nc.rh.ave1.tmp.mgh');
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