The present invention is concerned with detection of a “fragile watermark” in a printed image to aid in a determination whether a document under examination is an original or a copy. The watermark may be applied by phase-space encoding data to be included in the watermark. The image may be examined...http://www.google.fr/patents/US7995246?utm_source=gb-gplus-shareBrevet US7995246 - Detecting printed image copies using phase-space-encoded fragile watermark
Detecting printed image copies using phase-space-encoded fragile watermark
