What color schemes are available in sfgrey and sfgrey3?
The color scheme in sfgrey and sfgrey3 is selected by color= parameter. The default is color=I.
The picture shows different color schemes available.

Changing from uppercase to lowercase letters reverses the color scale:

Adding “C” to the colorscheme name highlights the clipped values:

These examples are taken from rsf/rsf/sfgrey.