1. A method of identifying one or more particular images from an image collection, comprising using a data processing system for: (a) indexing the image collection to provide image descriptors for each image in the image collection such that each image is described by a plurality of image descriptors, with or without user input; (b) receiving a query from a user specifying at least one keyword for an image search, wherein the at least one keyword is not an image descriptor; (c) using the keyword(s) to search a second collection of tagged images to identify keywords that are co-occurent with the user-provided keyword(s); (d) using the identified co-occurrence keywords to provide an expanded list of keywords; (e) using the expanded list of keywords to search the image descriptors to identify a set of candidate images satisfying the keywords; (f) grouping the set of candidate images according to at least one of the image descriptors, and selecting one or more representative images from each grouping; and (g) displaying the representative images to the user.