1. A method, comprising: by a computer ascertaining locations of word images corresponding to words in a document image; by the computer grouping the word images into clusters; for each of multiple of the clusters, compressing successive ones of the word images to produce the respective compressed word image cluster based on a joint compression of respective ones of the word images that are grouped into the cluster, wherein compressing comprises encoding differences between the successive word images in producing the respective compressed word image cluster; and by the computer associating the positions of the word images in the document image with the respective ones of the compressed word image clusters corresponding to the clusters respectively containing the word images.
1. A method, comprising: by a computer ascertaining locations of word images corresponding to words in a document image; by the computer grouping the word images into clusters; for each of multiple of the clusters, compressing successive ones of the word images to produce the respective compressed word image cluster based on a joint compression of respective ones of the word images that are grouped into the cluster, wherein compressing comprises encoding differences between the successive word images in producing the respective compressed word image cluster; and by the computer associating the positions of the word images in the document image with the respective ones of the compressed word image clusters corresponding to the clusters respectively containing the word images. 6. The method of claim 1 , wherein the compressing further comprises applying a run length encoding process to a bit stream derived from the successive word images in producing the compressed word image cluster.