Dear FSL experts, I was not able to find a specific answer in the posts for the following problem. I am trying to substract two masks from each other: one manually created and one as output from Freesurfer. They are both in native space. I thus ran: fslmaths T1mask.nii - sub CSOmask.nii T1-CSO.nii The following error appears: WARNING:: Inconsistent orientations for individual images in pipeline! Will use voxel-based orientation which is probably incorrect - *PLEASE CHECK*! Image Exception : #3 :: Attempted to subtract images of different sizes libc++abi.dylib: terminating with uncaught exception of type std::runtime_error: Attempted to subtract images of different sizes Abort trap: 6 these nii seem to have different voxel sizes when I checked using fslstats -v Is there a solution for this? Maybe some kind of crop tool in FSL? Many thanks for the support! /Ben ######################################################################## To unsubscribe from the FSL list, click the following link: https://www.jiscmail.ac.uk/cgi-bin/webadmin?SUBED1=FSL&A=1