- Our research deals with developing metrics for quantizing the contrast of target to background in color images, and investigating the degree such contrast affects the detection of targets by human observers. When dealing with a gray scale image, the only parameter affecting the detection of targets is the luminance contrast; in color images, there are several parameters. This research examines these parameters and defines the importance of each one of them. Our system parameters quantifying color images are based on CIELAB space (brightness-color). We examine how each axis in this space affects the contrast of the targets.