6. The tangible computer-readable medium of claim 3 , wherein the operations further comprise removing duplicate names from the cluster names after clustering the search results.
3. A tangible computer-readable medium having encoded thereon computer-program instructions executable by a processor, the computer-program instructions when executed by the processor, for performing operations comprising: submitting, for each word in a first set of annotations, a search query to an image search engine to generate a set of search results, the search query comprising the word and an image associated with the word; clustering the search results in view of words in the first set of annotations to obtain cluster names, obtaining a second set of annotations comprising the cluster names; modeling relationships between the first set and the second set of annotations in a bipartite graph, the bipartite graph comprising vertices representing the first set of annotations disjoint from the second set of annotations, the first set of annotations being direct descriptions of a target Web image, the second set of annotations being indirect descriptions of the target Web image; reinforcing, using respective ones of the relationships, initial rankings associated with the first set of annotations and the second sets of annotations by a reinforcement learning algorithm, the first set of annotations ranked according to a ranking algorithm comprising: obtaining a first initial candidate annotation ranking and a second initial candidate annotation ranking for each annotation in the first set of annotations, and fusing the first initial candidate annotation ranking and the second initial candidate annotation ranking using a weighted linear combination scheme; selecting a subset of the first and the second sets of annotations based on results of reinforcing the initial rankings, wherein the subset represents annotations determined with a modified threshold strategy; annotating the Web image with the subset to generate an annotated Web image; and providing indexing and search engine applications with access to the annotated Web image to present a user with relevant results to a search query.