Segmented or unsegmented head RGBA volume datasets

Not sure this is the right section to ask, anyway my question it’s not related to Slicer usage.

Looking at these examples

wanted to ask if someone know or has an idea where to search for other RGBA or anyway colored volume dataset of the head.

I think these data can come only from cryogenic slicing projects, since I didn’t know any other technique able to produce a colored volume, but might be wrong.