A system and method for identifying an object in an electronically acquired image that includes at least one two-dimensional array of pixels. A plurality of one-dimensional gradient runs oriented along a common direction in the two-dimensional array of pixels is identified. A second-order set of gradient runs is formed by selecting a group of previously identified one-dimensional gradient runs. Each of the one-dimensional gradient runs in the group has a pixel that is offset along an axis perpendicular to the common direction from a pixel in a neighboring one-dimensional gradient run in the group. The object is identified in the array using the second-order set of gradient runs.