초록 ▼

A secure document design has a visible graphical structure that forms part of the aesthetic features on the document and carries encoded message information. A method for generating this design starts with a visible structure used for geometric registration. It then generates a variable auxiliary me

A secure document design has a visible graphical structure that forms part of the aesthetic features on the document and carries encoded message information. A method for generating this design starts with a visible structure used for geometric registration. It then generates a variable auxiliary message comprising message values, and maps the message values to a two dimensional pattern of locations in the visible structure on the document. It repeats the auxiliary message and represents the auxiliary message differently in the two dimensional pattern according to a key. An implementation of this method may be used to create design artwork for printed security documents that is aesthetically pleasing, carries a robust machine readable message, and can be used to authenticate other information on the security document.

대표청구항 ▼

1. A method of generating a machine readable code on a printed document comprising:providing a visible structure used for geometric registration; generating a variable auxiliary message comprising message values; mapping the message values to a two dimensional pattern of locations in the visible str

1. A method of generating a machine readable code on a printed document comprising:providing a visible structure used for geometric registration; generating a variable auxiliary message comprising message values; mapping the message values to a two dimensional pattern of locations in the visible structure on the document; and repeating the auxiliary message and representing the auxiliary message differently in the two dimensional pattern according to a key. 2. The method of claim 1 wherein the key is used to spread the message redundantly over the two dimensional pattern.3. The method of claim 2 wherein the key is used in a randomization process spread the message over the two dimensional pattern.4. The method of claim 3 wherein the randomization process randomizes the mapping of message values to locations.5. The method of claim 3 wherein the randomization process randomizes values of the message.6. The method of claim 5 wherein the randomization process randomizes message values into binary values of substantially equal probability.7. The method of claim 1 wherein the key is used to randomize the message.8. The method of claim 1 wherein the auxiliary message is spread over the two dimensional pattern using a random number.9. The method of claim 8 wherein the message comprises binary values and the binary values are randomized into substantially equal probability of two different binary values.10. The method of claim 1 wherein line structures are used carry the machine readable code.11. The method of claim 1 wherein the machine readable code carries information that correlates with or is redundant to readable information on the printed document for authentication of the document by comparing at least a part of the machine readable code with the readable information printed on the document.12. A tangible medium on which is stored instructions for performing the method of claim 1.13. A method for detecting a machine readable code on a printed document, the method comprising:receiving an image scanned of the printed document; detecting a visible registration pattern in the image to perform geometric registration for the machine readable code; finding locations of a variable machine readable message arranged in the registration pattern, wherein the message is repeated and represented differently in a two dimensional pattern according to a key; extracting message values from image structures at the locations to decode the variable machine readable message. 14. The method of claim 13 wherein the key is used to spread the message redundantly over the two dimensional pattern.15. The method of claim 14 wherein the key is used in a randomization process spread the message over the two dimensional pattern.16. The method of claim 15 wherein the randomization process randomizes the mapping of message values to locations.17. The method of claim 15 wherein the randomization process randomizes values of the message.18. The method of claim 17 wherein the randomization process randomizes message values into binary values of substantially equal probability.19. The method of claim 13 wherein the key is used to randomize the message.20. The method of claim 13 wherein the auxiliary message is spread over the two dimensional pattern using a random number.21. The method of claim 20 wherein the message comprises binary values and the binary values are randomized into substantially equal probability of two different binary values.22. The method of claim 13 wherein line structures are used carry the machine readable code.23. The method of claim 13 wherein ink dot structures are used to carry the machine readable code.24. The method of claim 13 wherein varying ink structures are used to carry message elements having the same value at different locations in the two dimensional pattern.25. The method of claim 13 wherein the machine readable code carries information that correlates with or is redundant to readable information on the printed document for authentication of the document by comparing at least a part of the machine readable code with the readable information printed on the document.26. A tangible medium on which is stored instructions for performing the method of claim 13.