“…A variety of methods in the fields of image processing, signal processing, and computer vision have been developed to solve aspects of the problem of unsupervised detection and tracking of arbitrary objects. These methods might be placed into a few broad categories: those that aim to distinguish the foreground regions of images from the background [33,12,65,39], segment images into distinct regions to perform localization [35,23,56], track an object over a sequence of images (after its position has been specified in an initial image) [52,43,36,16,50], track multiple objects over a sequence of images (especially when the objects interact or occlude one another) [54,18,66,32,44,19], segment a sequence of images into distinct spatiotemporal regions [10,55,61], and combine the previous methods in some way to create systems capable of both detecting and tracking specified objects [47,7,67,38,41], or of discerning which regions of a video constitute distinct, arbitrary objects and tracking these [8,9,25,49,48].…”