The Perceptual Image Formation Processes Of Brightness Contrast

The paper gives some preliminary results of a continuing experimental study of adjacency effect. One of the important variables to consider in evaluating photo-interpretation by human observers is the adjacency effect, such as that resulting from the sharp contrast of black and white areas on a photographic surface. When human observers view a photographic surface on which black and white are adjoining, the adjacency or "edge" effect occurs. They notice a band of greater brightness just before the light area apparently shades into gray and a band of greater darkness just before the apparently gray area shades into greater darkness. Examination by a photometer or other optical instrument shows that these bands of light and dark do not exist and are only apparently present in the pattern. The apparent brighter and darker bands occur at the point of what was first known as the Mach Band effect (1916). The paper is concerned with a quantitative evaluation of the Mach Band effect when brief exposure time, less than .5 seconds is used.© (1974) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.