In this paper we develop a technique for measuring the perceptual equivalence of a graphical scene to a real scene. Ability to compare images is valuable in computer graphics for a number of reasons but the main motivation is to enable us to compare different rendering algorithms and to bring us closer to a system for validating lighting simulation algorithms against measurements. In this study we conduct a series of psychophysical experiments to assess the fidelity of graphical reconstruction of real scenes. Methods developed for the study of human visual perception are used to provide evidence for a perceptual, rather than a mere physical, match between the original scene and its computer representation. Results show that the rendered scene has high perceptual fidelity compared to the original scene, which implies that a rendered image can convey albedo. This investigation is a step toward providing a quantitative answer to the question of just how ``real'' photo-realism actually is.