I'm fairly sure that it's the double interpolation happening in @auto_tlrc. You can try the -onewarp option on your data to see if that helps.
-onewarp : Create follower data with one interpolation
step, instead of two.
This option reduces blurring of the output data.
It is not used by default for backward
compatibility.
My very quick test:
original epi:
4.34745 4.33357 4.0353
adwarp:
4.96608 4.67872 4.63067
@auto_tlrc:
3.99983 3.82253 3.88686
@auto_tlrc onewarp:
4.84429 4.51512 4.62035
Also, consider adding the -detrend option to your 3dFWHMx command.
Edited 2 time(s). Last edit at 09/26/2014 10:50AM by Peter Molfese.