A comparison of techniques for the transformation of radiosity values to monitor colors

Abstract

In the rendering process of radiosity scenes, the computed radiosity values have to be converted to color values that can be displayed on a CRT monitor. Usually radiosity calculations as well as various color calculations are performed in the RGB color space. Unfortunately the radiosity values can be outside a monitor gamut, which is a three-dimensional solid surrounding the set of all displayable colors for that device. The radiosity approach can be used either for rendering images with global illumination effects or for accurate physical simulation of light propagation. This paper introduces several techniques to transform radiosity values to monitor colors. These techniques use either clipping or compression, either scene dependent or independent algorithms and work either in the RGB, CIELUV or CIELAB color space. A simple, yet visually appealing, nonlinear color compression technique is introduced to generate smooth intensity gradients on a CRT monitor. The problems of accurate perceptual display of radiosity scenes are discussed as well as some new ideas from color theory are presented that might be helpful for a solution of this task. >