You've seen
(RemapColors rcPERCENT 253 64), which I use to draw a shadow under my Catdate characters. But what about the other remap effects available in SCI16?? Well, given a light view with index 254 in it, nabbed from QfG4...
(RemapColors rcPERCENT 254 200) -- mask color, brightness.

Brightness ranges from 0 to to 200, where 100 is effectively no change. 0 is not entirely all-black, and 200 you can see above. Anything higher yields weird spots.
(RemapColors rcRANGE 254 64 165 96) -- mask color, range start, range end, addition.

Given a picture with
this palette.
(RemapColors rcGRAY 254 75) -- mask color, percentage.
Soda pressing.(RemapColors rcPERCENTGRAY 254 75 120) -- mask color, percentage, brightness.
No visual. Applies both rcPERCENT and rcGRAY effects at once.
? No, I won't stop calling it that >:3