Authenticating printed objects using digital watermarks associated with multidimensional quality metrics

A method for embedding auxiliary information into an image to be printed on a printed object and used to authenticate the printed object, the method comprising:

• embedding auxiliary information into the image so that the auxiliary information degrades in response to a copy operation on the printed object;
• and
• embedding print information about a print attribute into the image, such that the auxiliary information includes the print information.

A printed object authentication system comprising:

• a print quality processor for measuring one or more print quality metrics from a subject image scanned from a printed object;
• a digital watermark decoder for detecting a digital watermark from the subject image and determining a digital watermark metric based on the detected digital watermark in the subject image;
• a classifier in communication with the decoder and processor for receiving the print quality and digital watermark based metrics and classifying the subject image as an original or copy as a function of each of the metrics.