摘要:
The present invention provides methods and systems for authenticating identification documents (100). We also teach an identification document (100) including two or more digital watermarks (27, 60). The watermarks correspond with each other or with indicia carried by the identification document (100). The correspondence can be verified to determine authenticity. We also provide digital watermark detection methods and systems to identify the different watermarks (100) through embedded orientation components. We then focus watermark message-decoding efforts on areas identified as likely including watermark orientation components (27, 60). In one implementation we provide a watermark detection trigger to identify so-called legacy documents. The trigger may indicate the presence or expected absence of a digital watermark. In other implementations we provide a versatile document authenticator to toggle between watermarking and non-watermarking authentication processes depending on a detection trigger (100).
摘要:
This disclosure describes methods for using embedded auxiliary signals in documents for copy detection and other applications. In an application, the auxiliary signal is formed as an array of elements selected from a set of print structures (106) with properties that change differently in response to copy operations. These changes in properties of the print structures that carry the embedded auxiliary signal are automatically detectable. The extent to which the auxiliary data is detected forms a detection metric used in combination with one or more other metrics to differentiate copies from originals. Robust and fragile watermarks are used in Image Replacement Documents for a variety of applications. Digital watermarks act as on-board mediators in authentication of a variety of printed documents. Finally, digital watermarks are used to help manage quality of the scanners used in imaging systems.
摘要:
Digital watermarks are encoded on envelopes to serve a variety of purposes related to postage (franking), anti-counterfeiting, addressing, and linking to associated internet sites. Digital watermarks can also be formed on blank paper stock so that printed documents formed therewith have desired properties, including the ability to distinguish photocopies from originals, to link to corporate web sites, and to permit document serialization for tracing and other purposes.