1. A system for detecting objects in a image, comprising: an object detector module configured to detect regions of the image based on at least the content of the image, wherein at least some of the regions include objects of a particular type; and a false positive detector module configured to determine whether each region detected by the object detector module includes an object of the particular type, based on at least information about the context in which the image was taken, wherein the false positive detector module comprises: a simple false positive detector module configured to determine whether each re ion detected by the object detector module includes an object of the particular type; and a composite false positive detector module, that requires more computing resources than the simple false positive detector module, configured to determine based on at least one image feature not used by the simple false positive detector module, whether each region detected by the simple false positive detector module includes the object of the particular type, wherein the object detector module and false positive detector module are implemented on at least one processor and memory.