| 摘要 |
Method of marking a document with a visible pattern that is not readily apparent to human viewers but is machine readable from data generated from visible light scanning of the document. One method of marking the document includes encoding the data redundantly into the background pattern using the line art of the document. This encoding could be achieved by changing the widths and positions of the line in the line are. Two digital watermarks of different robustness could also be incorporated in the line art to increase the security. This method could be used with security documents including bank-notes. There is also disclosed another method of marking a security document with machine readable, generally imperceptible, data where the distribution of ink on the security document is used to encode the data and the data is encoded with two digital watermarks. A hologram could also be added to the document. |
