Shading in two-dimensional images produces a compelling perception of three-dimensional shape. When mechanisms of perception are considered from an engineering standpoint, shape-from-shading is known to be an ill-posed problem that is difficult to solve. Constraints are needed to solve this kind of problem. Although estimation of reflectance properties from shading is also considered an ill-posed problem, mechanisms of estimation by the visual system are still poorly understood. Therefore, we proposed a psychological experiment intended to determine whether the visual system can estimate surface reflectance properties from shading. In the experiment, we expect to use contours as a cue for perceiving three-dimensional structures. From a preliminary experiment we obtained data that did not rule out that the ability of the visual system to estimate surface reflectance from shading.
