Contrast based edge detection

摘要

The detection of edges in scenes containing poorly lit regions has been studied from the viewpoint of the physical processes underlying the formation of an image. It is shown that consistent edge detection can be achieved in unevenly illuminated visible-band images if edge detection algorithms are formulated to respond to contrast rather than absolute brightness values. The process of contrast modification is illustrated using Sobel and 5 × 5 gradient operators as examples and the applicability of the technique to i.r. images is examined.