13. The method of claim 12 , wherein the extracting further comprises applying a video decompression process to the compressed word image cluster in producing the successive word images.
12. A method, comprising: by a computer receiving a set of compressed word image clusters each comprising a joint compression of a respective cluster of word images; by the computer receiving associations between respective ones of the word images in the respective joint compressions of the compressed word image clusters and positions of respective ones of the word images in a document image; by the computer extracting the word images from respective ones of the compressed word image clusters, wherein the extracting comprises applying a run length decoding process to the compressed word image cluster to produce a bit stream, and deriving the successive word images from the bit stream; rendering a version of the document image based on the extracted word images and the associations between the compressed word image clusters and the positions of the word images in the document image.