Researchers studying surface color perception have typically used stimuli that consist of a small number of matte patches~real or simulated! embedded in a plane perpendicular to the line of sight~a "Mondrian," Land & McCann, 1971!. Reliable estimation of the color of a matte surface is a difficult if not impossible computational problem in such limited scenes~Maloney, 1999!. In more realistic, three-dimensional scenes the difficulty of the problem increases, in part, because the effective illumination incident on the surface~the light field! now depends on surface orientation and location. We review recent work in multiple laboratories that examines~1! the degree to which the human visual system discounts the light field in judging matte surface lightness and color and~2! what illuminant cues the visual system uses in estimating the flow of light in a scene.

We report the results of three experiments in which observers judged the albedo of surfaces at different locations in rendered, three-dimensional scenes consisting of two rooms connected by a doorway. All surfaces composing the rooms were achromatic and Lambertian, and a gradient of illumination increased with depth. Observers made asymmetric albedo matches between a standard surface placed in the rooms at different depths along the line of sight and an adjustable surface at a fixed location. In Experiment 1, gradients of intensity on the walls, floor, and ceiling of the scene, as well as its three-dimensional structure, provided information about variations in the intensity of illumination across depth (the illumination profile). In Experiment 2, specular spheres provided an additional veridical cue to the illumination profile. We sought to determine whether observers would make use of this additional cue. They did: all observers exhibited a greater degree of lightness constancy in Experiment 2 than in Experiment 1. In Experiment 3, the specular spheres reflected an illumination profile in conflict with that signaled by the other cues in the scene. We found that observers chose albedo matches consistent with an illumination profile that was a mixture of the illumination profiles signaled by the specular spheres and by the remaining cues.

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