That's right. Many of these uses don't use color, but some do.

For example, cell counting. You have a microscope slide
with randomly placed cells on it, dyed to fluoresce.
Each cell fluoresces the same amount. Hence by looking at the
image on a computer you count cells in each pixel. If
a cell overlaps two or four pixels, you can usually assign
the center of it to one of the pixels. Having no
anti-aliasing helps this. You could use color if you
had two or three cell types, dyed to fluroresce red, green,
or blue. There are very common dyes that actually do this.

Doug McDonald