1. An image processing system configured to receive a plurality of input images and track objects within image frames, the system comprising: a hardware processing system configured to: perform a first level of association between detection responses in image frames, wherein the detection responses include a vector having position, size, and frame index components, including forming one or more tracklets between pairs of detection responses having suitable link probabilities; receive the one or more tracklets formed as a result of the first level of association, and perform a second level of association, including producing a tracklet association between tracklets; perform a third level of association, including estimating a scene structure model from the second level of association; and provide as an output a trajectory set of the tracklets.
7. The system of claim 1 , wherein for the first level of association, the hardware processing system is configured to link two responses in response to an affinity between the two responses being greater than an affinity of conflicting pairs.