1. A method, comprising: storing a plurality of image frames in a memory; and performing a face detection task on the plurality of image frames, the face detection task comprising multiple successive sets of tasks; wherein the successive sets employ progressively increasing detection region size; detecting whether sufficient computing resources exist for a sub-task; merging and filtering faces in the data structure in response to the determination that sufficient resources do not exist for the sub-task; wherein each of the multiple sets employs one or more detection regions having the corresponding detection region size; and wherein at least one of the multiple sets employs two or more partially overlapping detection regions having the corresponding detection region size.