GLHS: A Generalized Lightness, Hue, and Saturation Color Model

Abstract

We discuss the problem of color organization and modeling in general and in computer graphics in particular. After a brief review of the Red, Green, and Blue (RGB) and Lightness, Hue, and Saturation (LHS) color models in computer graphics, a generalization of the latter, the Generalized Lightness, Hue, and Saturation (GLHS) model, is introduced, derived, and discussed. It is shown 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. Illustrations are given 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 a Multiple Color Model Image Display System. Finally, we discuss briefly the potential for finding within the GLHS family a model that provides the closest approximation to a uniform color space. Such a model shares the perceptual properties of a proven uniform model and, at the same time, the algorithmic properties of the GLHS family.