FÄLSCHUNGSSICHERE DOKUMENTE MIT BILDERN, DIE GEHEIME DATEN ÜBERTRAGEN, SOWIE VERFAHREN DAFÜR

摘要

The security of various documents, e.g. passports, is enhanced by hiding machine-detectable multi-bit information within an image on the document, and later using such information for document authentication. The hidden information may correlate, for example, with textual information printed on the document. Photo-swapping and other forgery problems are thereby redressed.