Pixel-parallel CMOS active pixel sensor for fast object location

A pixel-parallel image sensor readout technique is demonstrated for CMOS active pixel sensors to facilitate a range of applications where the high-speed detection of the presence of an object, such as a laser spot, is required. Information concerning the object's location and size is more relevant that a captured image for such applications. A sensor for which the output comprises the numbers of pixels above a global threshold in both rows and columns is demonstrated in 0.18mum CMOS technology. The factors limiting the ultimate performance of such a system are discussed. Subsequently, techniques for enhancing information retrieval from the sensor are introduced, including centroid calculations using multiple thresholds, multi-axis readout, and run-length encoding.