ABSTRACT
Contrast is a density difference between adjacent areas in an image that allows us to see contours or edges. Photographers can playfully experiment with common contours by adopting a camera angle that creates a shared contour between two objects located at different distances. Edges give rise to lines, one of the most fundamental visual elements. In the photograph "Dunes, Colorado", a common contour is shared by the very edge of the white and black areas. Contrast and sharpness go hand in hand. When using a camera, the sharpness of an edge can be controlled by selective focus, depth of field, and special filters—which in turn affects the contrast. A physical measurement of sharpness due to edge effects is called acutance. Regardless of the software used, sharpening involves a search for edges. When an edge is detected, the software program increases the density on one side of the edge and decreases it on the other side.
