Downsampling NRRDs prior to importation?

Operating system: Windows 10 Enterprise Version 21H2 with 128 GB of installed RAM
Slicer version: 4.11.20210226
Expected behavior: I am working on a geometric morphometrics project with micro-CT scans of fish skeletons. I am trying to increase the resolution so that I can proceed with anatomical landmarks, but I cannot find a way to downsample the images prior to importation. I checked on the 3D Slicer Documentation and one suggestion is to use the Resize Image (BRAINS) module to downsample the fish scans. However, I am new to 3D Slicer and I cannot find any tutorials which explain how to downsample nrrd files prior to importation. I have attached below two screenshots, the one on the top is the desired resolution and the one on the bottom is the current resolution.
Thanks,
Christian


The unu utility is very powerful for this kind of task. You can use the resample subcommand.

http://teem.sourceforge.net/unrrdu/