43. The computer program product of claim 24 , wherein recognizing the electronic document corresponding to the input image using the invisible junction features comprises creating a patch map.
43. The computer program product of claim 24 , wherein recognizing the electronic document corresponding to the input image using the invisible junction features comprises creating a patch map. 44. The computer program product of claim 43 , wherein creating the patch map comprises: defining a grid having a plurality of cells; generating a query using invisible junction features of a cell of the grid; applying the query to a database to generate a list of candidate documents; and defining a cell in the patch map corresponding to the list of candidate documents.