Psychophysical Models in Image Synthesis
It has long been known that the human visual system (HVS) is not a camera; the eye-retina-brain combination does not simply record a visual scene the way a movie camera or video camera does. Instead, the HVS processes the image in a series of steps of increasing abstraction. At each step some information about the scene may be lost and replaced by a higher level of representation. Thus, the HVS is remarkably insensitive to the loss of certain kinds of information in an image scene. Conversely, since the HVS has evolved to detect meaningful patterns, it is exceptionally sensitive to certain image characteristics, a case in point being vernier acuity. Vernier acuity refers to the ability of the HVS to estimate relative displacements between lines or other image features to a resolution much finer than the spacing between the rods or cones in the fovea [FAHLE 1981]. Vernier hyperacuity accounts for the exceptional visibility of "jaggies", the ragged line appearance of lines drawn on a computer display without proper antialiasing [MONTALVO 1979].