Hi Rick,

We had the same issue, and used your 3dfractionize method,
and that appeared to work fine for us too. Thanks !
Why does the 3dfractionize help message say (under -preserve flag)
** Combining this with the -warp option does NOT
make a general +tlrc to +orig transformer!
This is because for any value to survive the
vote, its fraction in the output voxel must be
>= clip fraction, regardless of other values
present in the output voxel.

Actually, a general +tlrc to +orig transform is exactly what we are
looking for. I understand there will always be interpolation issues
in regridding, and that is what I thought the -clip was about.
I just want to be sure that when I call 3dfractionize
with -warp it is really implementing an inverse of the orig->tlrc warp,
and not just resampling to the -template gridsize.

thanks
Kate