Überprüfbare optische Zeichenerkennung

摘要

A certificate (27), calculated on the text of a document (24) to be reproduced, is included in the document in a form which is machine-readable. Upon optical character recognition scanning (at 16), or other digitizing reproduction, the certificate (27) is also scanned and stored for comparison. A new certificate is calculated on the contents of the reproduced document (25) and compared to the scanned certificate (27). If the two certificates are different, it is known that at least one error exists in the reproduced document (25). More than one certificate can be provided for a document in order to facilitate error location on the document and error correction therein.