afni.nimh.nih.gov

Dear AFNI gurus,

I have an image that is 256 x 256 x 256 with voxel size of 1 mm, many of these are zero-valued voxels. I intend to crop the image so as to improve processing speed. Is this recommended? If so, what tool can do this? I've looked over 3dresample, 3drefit, and others and have not seen the capability that I am looking for. I see that many of AFNI's programs do not process the whole image, so perhaps it is not necessary to crop the image?

Thank you for your help,

Matthew