Resolution limits to object tracking with subpixel accuracy

Subpixel methods increase the accuracy and efficiency of image detectors, processing units, and algorithms and provide very cost-effective systems for object tracking. Published methods achieve resolution increases up to three orders of magnitude. In this Letter, we demonstrate that this limit can be theoretically improved by several orders of magnitude, permitting micropixel and submicropixel accuracies. The necessary condition for movement detection is that one single pixel changes its status. We show that an appropriate target design increases the probability of a pixel change for arbitrarily small shifts, thus increasing the detection accuracy of a tracking system. The proposal does not impose severe restriction on the target nor on the sensor, thus allowing easy experimental implementation.Support of the Spanish Ministerio de Economía y Competitividad through the project BIA2011-22704, the Generalitat Valenciana through the project PROMETEO/2011/021, and the University of Alicante through the project GRE10-09. J. T. Sheridan acknowledges the support of Science Foundation Ireland and Enterprise Ireland under the National Development Plan