Scene-based nonuniformity correction processor incorporating motion

Abstract

A nonuniformity correction processor (30) adapted for use with a focal plane array of detectors. The inventive processor (30) includes a nonuniformity correction circuit (32, 38, 42, 53, 54, 56, 58) for generating current nonuniformity correction terms (32) and applying the terms to information (26) received from the scene via the focal plane array of detectors. A triggering circuit (44) selectively enables the nonuniformity correction circuit (32, 38, 42, 53, 54, 56, 58) in response to a motion signal (50) from a motion detector (40, 46, 48, 52). In a specific embodiment, the nonuniformity correction circuit (32, 38, 42, 53, 54, 56, 58) further includes a filtering circuit (38) for generating intermediate nonuniformity correction terms (42, 53) in response to the scene information (26) received from the focal plane array of detectors. In the illustrative embodiment, the nonuniformity correction circuit (32, 38, 42, 53, 54, 56, 58) further includes an updating circuit (32, 53, 54, 56, 58) for providing and storing the current correction terms (32). Current correction terms (32) are obtained from a combination of the intermediate nonuniformity correction terms (42, 53) and pre-existing correction terms (56) stored in the updating circuit (58). The motion detector (40, 52) includes an external motion input signal (52) and a scene motion detection circuit (40). The scene motion detection circuit (40) includes a circuit for testing pixels and counting the number of pixels that differ from a predetermined pixel value by a predetermined threshold. The triggering circuit (44) includes a pass gate (44) having the motion signal (50), and the intermediate correction terms (42) as inputs. The output (53) of the triggering circuit (44) is connected to the updating circuit (32, 53, 54, 56, 58) which computes current correction terms from the intermediate correction terms (32) and pre-existing correction terms (56) when the output of the pass gate (44) is activated via the motion signal (50).