17. A system for optical character recognition including a processor configured to perform operations comprising: receiving a plurality of proposed character assignments for at least one instance of a character in an image on which optical character recognition is being performed, each of the character assignments representing a character determined from a character set for the at least one instance of the character by the optical character recognition, the at least one instance of the character residing in one or more character strings of a plurality of characters, at least one of the character strings of a plurality of characters known to exclude a subset of at least one character from the character set based at least in part on the at least one character string of a plurality of characters' location in the image; and eliminating at least one of the proposed character assignments by comparing the at least one of the proposed character assignments to the subset of at least one character excluded from the at least one character string of a plurality of characters.
19. The system of claim 17 wherein the processor is further configured to perform operations comprising determining the subset of at least one character excluded by a character string of a plurality of characters at least in part from information conveyed by the character string of a plurality of characters.