Hi Jim,

The "Normalized" variant .BRIK file is twice the original because
it is of type "float" (4 bytes per voxel), as opposed to the
original type "short" (2 bytes per voxel). If you want them to be
the same size, use "-fscale" instead of "-datum float".

Since you will have a maximum difference presumably less than
10, say, then you will still have a resolution of 0.0003 with a
"short" typed dataset (using '-fscale').


The huge file sizes are because you are probably going from a
smaller volume and a lower resolution to a Talairach dataset.
If your functional dataset is 64x64x20x1000 shorts, for instance,
and you go to a dataset of 161x191x151x1000 floats, then you
are going from a file size of 163 MB to one of 18.6 GB, which
may be too big to store in memory.

Even if you cut that back down to shorts, storing a Talairach
volume time series may not be possible.

Maybe you should convert your VOI mask to orig coordinates.

- rick