Thank you so much, Andras! That example helps a lot!
I would like to save as an uncompressed data format or raw data. Not sure which is better for viewing and editing yet.
You can save the image sequence as an uncompressed raw file and a separate header file (you must have that to be able to interpret the data correctly) using File / Save. Choose “.seq.nhdr” file format, enable “Show options” and uncheck “Compress” option:
A numpy file does not store all metadata that must be preserved (such as image origin, spacing, axis directions, axis kinds, sequence axis type, name, unit, values), therefore I would recommend to use nrrd format. If you don’t need any metadata just the voxels as a numpy array then you can read the nrrd file using pynrrd.
What further processing would you like to do in what software?
Do you want to define two trajectories (nerves, vessels, etc.) running across the volume? If yes, then it is much faster to define that using a curve and then set the voxels from the curve points.
If you tell us about your overall goal then we can give advice on how to achieve that. It is important to make sure that the high-level workflow is good before discussing minor implementation details.