Hi AFNI experts,
When performing a "orig->tlrc" transformation on EPI data, I noticed that "@auto_tlrc" would reduce the spatial smoothness in the newly generated "tlrc" data while "adwarp" would not. Could you please explain me why?
Here is what I did:
3dFWHMx -mask epi_mask+orig epi+orig
++ 3dFWHMx: AFNI version=AFNI_2011_12_21_1014 (Apr 11 2014) [64-bit]
++ Authored by: The Bob
++ Number of voxels in mask = 23778
7.22925 6.22382 4.82046
3dcalc -prefix epi_for_adwarp -a epi+orig -expr 'a';
adwarp -apar anat+tlrc -dpar epi_for_adwarp+orig;
3dFWHMx -mask anat+tlrc epi_for_adwarp+tlrc
++ 3dFWHMx: AFNI version=AFNI_2011_12_21_1014 (Apr 11 2014) [64-bit]
++ Authored by: The Bob
++ Number of voxels in mask = 1948925
7.47012 6.19473 5.89288
3dcalc -prefix epi_for_autotlrc -a epi+orig -expr 'a';
@auto_tlrc -apar anat+tlrc -input epi_for_autotlrc+org;
3dFWHx -mask anat+tlrc epi_for_autotlrc+tlrc
++ 3dFWHMx: AFNI version=AFNI_2011_12_21_1014 (Apr 11 2014) [64-bit]
++ Authored by: The Bob
++ Number of voxels in mask = 1948925
5.80593 4.92356 4.93437
