afni.nimh.nih.gov

Thanks! That function sounds like what I want, but I'm not sure how to make it work or if it does what I am intending.

Specifically what I'm looking for is what you mentioned first - to do anisotropic smoothing. For example, I would like to define my own smoothing kernel such as a Gaussian FWHM 2x2x6mm^3. So I'd like my smoothing along the z-axis to be greater.