RGB Values

RGB. Many graphics intrinsics take RGB colors. In other words, the colors are specified by three, 8-bit Red, Green, and Blue values. An 8-bit Alpha value is carried internally, and is used for certain transparency operations.

Compatibility Mode. To maintain compatibility with previous versions, if the Red value is negative, the Green value is taken as a VGA color index whose meaning is controlled by which graphics mode the console is emulating.