I have two images from the same subject (SPGR and EPI) which are of
different voxel sizes. I used the Coregister button in SPM8 and estimated
and resliced the EPI (2x2x4mm) to SPGR space (1x1x1).
The problem is I need the transformation matrix which maps each pixel in
SPGR space back to a floating point voxel value in the EPI image. I hunted
back in the archives and found a email posting that to get the
transformation matrix, use
spm_get_space('epi.img,1')/spm_get_space('spgr.img,1')
where spgr.img is the reference image and epi.img is the image to reslice.
This didn't give me the voxel to voxel mapping which I needed.
My logic was as follows:
T_m= spm_get_space('epi.img,1')/spm_get_space('spgr.img,1')
[X_epi; Y_epi; Z_epi; 1]=T_m * [X_spgr; Y_spgr; Z_spgr; 1]
As I said, this didn't work and I'm not sure why.
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