Rebol Programming/brightness?

= USAGE: = BRIGHTNESS? color

= DESCRIPTION: = Returns the monochrome brightness (0.0 to 1.0) for a color value.

BRIGHTNESS? is a function value. = ARGUMENTS =
 * color -- (Type: tuple)

= SOURCE CODE = brightness?: func [ {Returns the monochrome brightness (0.0 to 1.0) for a color value.} color [tuple!] ][   (0.27 * color/1) + (0.63 * color/2) + (0.1 * color/3) / 255 ]