16. A computer-readable storage medium comprising computer-executable instructions that when executed by a hardware processor, cause the processor to perform acts of: aggregating all page information image-page tuples of an image cluster into aggregated page information; selecting descriptive terms from the aggregated page information to represent the image cluster; annotating selected image-page tuples of the image cluster with the descriptive terms; and indexing the selected image-page tuples based on the descriptive terms.
17. The computer-readable storage medium of claim 16 , further comprising training a statistical model that assigns different term weights based on location of the descriptive terms in a page.