1. An apparatus, comprising: image capturing device useable to capture one or more images and providing the images as digital images; and one or more circuit components that perform actions, including: receiving the captured digital one or more images; determining for the one or more images an aggregate relative derivative (ARD) for each pixel in at least one of the images, the ARD being calculated from a derivative metric in a block assigned to each pixel, the derivative metric being determined from maximum and minimum derivatives for horizontal luminance derivatives and vertical derivatives within the block; and using the ARD to segment pixels in the at least one of the images into one of a foreground or a background segment of the image.