A major goal of realistic image synthesis is to generate images that are both physically and perceptually indistinguishable from reality. One of the practical obstacles in reaching this goal is that the natural world exhibits a wide range of colors and intensities. The range of the luminances in the real world can vary from 10-4cd/m2 (for starlight) to 105cd/m2 (for a daylight scene). Reproducing these luminances on a cathode-ray tube (CRT) display is currently not possible as the achievable intensities are about 100 cd/m2 and the practical ratio between maximum and minimum pixel intensity is approximately 100:1. At the University of Bristol, we have constructed a High Dynamic Range (HDR) viewer that is capable of achieving a 10,000:1 contrast ratio. This sketch investigates, by means of psychophysical experiments, the benefits such a HDR device has to offer realistic computer graphics. Realistic image synthesis has shown that it is possible, via tone mapping, to generate images similar to a real scene by careful mapping to a set of luminances that can be displayed on a CRT. Different tone mapping operators, for example [Ward et al 1997; Tumblin et al 1999], have been developed over the years, however none of them have managed to offer the substantial contrast reduction needed to display images without some loss of information.