Brian Scamman writes:
Is there a way to increase the number of greyscale levels available to the
display window? Currently, I am able to only get six different levels. I would
like to get 256 levels if it is possible.
r.colors map=mapname color=rules
will do the trick if your 'rules' file contains
0% 0 0 0
100% 256 256 256
if I'm not mistaken (I haven't tried it myself)