1. A method, comprising: iteratively performing, by one or more computers: selecting a target image from a plurality of component images; selecting, according to one or more heuristics for selecting subsets of component images, a component image subset from among one or more subsets of the plurality of component images, wherein each component image subset includes one or more of the plurality of component images, and wherein the target image is not in a subset; comparing features of the target image to features of the component images in the one or more component image subsets starting at the selected component image subset until locating a component image subset that includes a component image that overlaps the target image according to respective features of the images or until all of the component image subsets have been searched; if said comparing locates a component image subset that includes a component image that overlaps the target image, adding the target image to the component image subset; and if said comparing does not locate a component image subset that includes a component image that overlaps the target image, forming a new component image subset that includes the target image; until all of the component images in the plurality of component images have been processed.