NetLogo 7.0.0-beta2:

palette:with-brightness

color palette:with-brightness number

Reports an RGBA color with brightness component in HSB color space equal to number and the other HSB components of the input color unchanged. An error message results if number is not in the range 0 to 100.

Example:

show red palette:with-brightness 50 ;; [128 30 24]

Take me to the full Palette Extension Dictionary