1. A computer program product, comprising a non-transitory computer readable storage medium having stored/encoded thereon computer readable program instructions configured to cause a processor, upon execution thereof, to: perform optical character recognition (OCR) on an image of a document; extract an identifier of the document from the image based at least in part on the OCR; compare at least portions of the identifier with content from one or more reference data sources; and determine whether the identifier is valid based at least in part on the comparison; wherein the content from the one or more reference data sources comprises global address information; wherein the content from the one or more reference data sources is derived from geographic information organized in one or more of a proprietary address database and an open source address database; and wherein deriving the content from the geographic information comprises: obtaining the geographic information from one or more of the proprietary address database and an open source address database; and parsing the geographic information according to a set of predefined heuristic rules, wherein the set of predefined heuristic rules are configured to normalize the global address information obtained from the one or more sources according to a single convention for representing address information.
7. The computer program product as recited in claim 1 , comprising locating the identifier within the image based on a connected components analysis.