Color in Computer Graphics

Abstract

In this Chapter¹ we discuss color organization and modeling in computer graphics. After a brief review of the Red, Green, and Blue (RGB) and Lightness, Hue, and Saturation (LHS) color models in computer graphics, we introduce, derive, and discuss a generalization of the latter, the Generalized Lightness, Hue, and Saturation (GLHS) model. We show that previously-used LHS color models are special cases of GLHS, and can be obtained from it by appropriate assignments to its free parameters. We derive some mathematical results concerning the relation between GLHS and RGB. Using these, we are able to give a single pair of simple algorithms for transforming from GLHS to RGB and vice versa. This single pair of algorithms transforms between RGB and any of the previously-published HSL, HSV, and HLS models, as well as any other special case of the generalized model. Nevertheless, they are as simple as the separate algorithms published previously. We give illustrations of color gamuts defined by various assignments to the free parameters of the GLHS system as they appear on the display monitor under the control of the Multiple Color Model Image Display System. Finally, we briefly discuss the potential for finding within the GLHS family a model that provides the closest approximation to a uniform color space. Such a model would share the perceptual properties of a proven uniform model and, at the same time, the algorithmic properties of the GLHS family.