Techniques for detecting, analyzing, and using visible authentication patterns

• US 7,937,588 B2
• Filed: 01/06/2005
• Issued: 05/03/2011
• Est. Priority Date: 01/06/2004
• Status: Active Grant

• Current Assignee: Thomson Licensing (Vantiva SA)
• Original Assignee: Thomson Licensing (Vantiva SA)
• Inventors: Zhao, Jian, Picard, Justin
• Primary Examiner(s): Song; Hosuk
• Application Number:
  US10/585,396
• Publication Number:
  US 20080301767A1
• Time in Patent Office: 2,308 Days
• Field of Search: 380200-203, 380/54, 713/176, 713/189, 713193-194, 713/168, 713/170, 726 26- 33, 382/100
• US Class Current: 713/176
• CPC Class Codes: G06T 1/0042 Fragile watermarking, e.g. so as to detect tampering
• CPC Class Codes: G06T 1/005 Robust watermarking, e.g. average attack or collusion attack resistant
• CPC Class Codes: G06T 2201/0065 Extraction of an embedded watermark; Reliable detection
• CPC Class Codes: G06T 2201/0081 whereby both original and watermarked images are required at decoder, e.g. destination-based, non-blind, non-oblivious
• CPC Class Codes: G09C 5/00 Ciphering apparatus or methods not provided for in the preceding groups, e.g. involving the concealment or deformation of graphic data such as designs, written or printed messages
• CPC Class Codes: H04N 1/32154 Transform domain methods H04N1/32309 takes precedence
• CPC Class Codes: H04N 1/32309 in colour image data
• CPC Class Codes: H04N 2201/3263 of a graphical motif or symbol, e.g. Christmas symbol, logo H04N2201/3211 takes precedence
• CPC Class Codes: H04N 2201/3266 of text or character information, e.g. text accompanying an image H04N2201/3226 takes precedence
• CPC Class Codes: H04N 2201/3269 of machine readable codes or marks, e.g. bar codes or glyphs
• CPC Class Codes: H04N 2201/3271 Printing or stamping
• CPC Class Codes: H04N 2201/3281 Encryption; Ciphering
• CPC Class Codes: H04N 2201/3284 for error correction

Abstract

Improved techniques for making copy detection patterns and using them to detect copying relationships between digital representations. The techniques include techniques for including a message in a copy detection pattern without altering the copy detection patterns entropy and reading the message, techniques for using a copy detection pattern on an analog form to determine whether the analog form is an original analog form without reference to a digital representation of the original of the analog form'"'"'s copy detection pattern, techniques for increasing the sensitivity of copy detection using copy detection patterns by modifying one of two copy detection patterns that are being compared to take into account alterations resulting from the copying process, techniques for distributing a copy detection pattern across a document, and techniques for using the entropy of a copy detection pattern to locate the copy detection pattern. Also disclosed are applications of copy detection patterns with copying that involves transformations between the digital and analog forms and with digital-to-digital copying.

Claims

1. A digital representation of an analog signal, the digital representation being characterized in that:

the digital representation includes a representation of a copy detection signal whose sensitivity to transformations produced by digital-to-analog and analog-to-digital conversions is not based on a watermark contained in the copy detection signal,

the representation of the copy detection signal being comparable with the copy detection signal of another digital representation to determine a copying relationship of the analog signal to the other digital representation of the analog signal.

2. A method of creating a digital authentication pattern that permits non-watermark-based determination of a copying relationship of a digital representation of an object with which the digital authentication pattern is associated, the digital authentication pattern containing a message, the digital authentication pattern belonging to a digital representation of an object with which the digital authentication pattern is associated, and the digital authentication pattern including a plurality of pattern elements that have pattern element values and the method comprising:

selecting a set of the pattern elements to represent message elements of the message; and

for a pattern element belonging to the selected set of pattern elements, setting the pattern element'"'"'s pattern element value to represent the message element such that setting the pattern element'"'"'s value to represent the message element leaves the digital authentication pattern'"'"'s usefulness in determining the copying relationship substantially unchanged.

3. The method according to claim 2, wherein:

in the step of setting the pattern element value, the pattern element value is set such that the entropy of the digital authentication pattern is substantially unchanged.

4. The method according to claim 2, wherein:

in the step of setting the pattern element value, the message element specifies a message element value belonging to a range thereof; and

the pattern element value of the pattern element belonging to the selected set of pattern elements is set to one of the values of the range.

5. The method according to claim 4 wherein:

in the step of setting the pattern element value, the selected set is set using a key.

6. The method according to claim 4 wherein:

in the step of setting the pattern element value, the pattern element value of the pattern element belonging to the selected set of pattern elements belongs to one of at least two categories of pattern element values, the category of the pattern element value represents the message element, and the pattern element is given a category as required for the message element value of the message element represented by the pattern element.

7. The method according to claim 6 wherein:

the pattern element values in the selected set belong to two categories.

8. The method according to claim 7, wherein:

in the step of setting the pattern element value, the values of the pattern element in the selected set is inverted in magnitude to indicate a category.

9. The method according to claim 2, wherein:

in the step of setting the pattern element value, the message is encoded using a key.

10. The method according to claim 2, wherein:

in the step of setting the pattern element value, a key is used to select the set of pattern elements that represent message values.

11. The method according to claim 2 wherein:

the pattern element is a primitive element of the digital representation to which the digital authentication pattern belongs.

12. A storage device that is characterized in that:

the storage device contains code which, when executed by a processor, implements the method according to claim 2.

13. A digital authentication pattern that permits non-watermark-based determination of a copying relationship of a digital representation of an object with which the digital authentication pattern is associated, the digital authentication pattern containing a message and the digital authentication pattern comprising:

a plurality of pattern elements, the plurality of pattern elements including a set of the pattern elements that represent message elements of the message; and

in a pattern element that represents a message element, the value of the pattern element is set such that setting the value of the pattern element to represent the message element leaves the digital authentication pattern'"'"'s usefulness in determining the copying relationship substantially unchanged.

14. The digital authentication pattern according to claim 13, wherein:

the pattern element'"'"'s value is set such that an entropy of the digital authentication pattern is substantially unchanged from a digital authentication pattern that does not contain a message.

15. The digital authentication pattern according to claim 13, wherein:

the message elements specifies a values belonging to a range thereof; and

a pattern element that represents the message element set to one of the values of the range.

16. The digital authentication pattern according to claim 15 wherein:

the pattern element values belong to categories thereof;

the category of a pattern element value represents the value of the message element represented thereby.

17. The digital authentication pattern according to claim 13, wherein:

the pattern element is a primitive element of the digital representation to which the digital authentication pattern belongs.

18. The digital authentication pattern according to claim 17, wherein:

the pattern element is a pixel.

19. The digital authentication pattern according to claim 17, wherein:

the digital representation is a representation of an audio signal and the pattern element is a primitive of the representation of the audio signal.

20. The digital authentication pattern according to claim 17, wherein:

the digital representation is a representation of a video signal and the pattern element is a primitive of the representation of the video signal.

21. A storage device which is characterized in that:

the storage device contains the digital authentication pattern according to claim 13.

22. A method of reading a message contained in a digital authentication pattern, the digital authentication pattern permitting non-watermark-based determination of a copying relationship of a digital representation of an object with which the digital authentication pattern is associated, the digital authentication pattern including a plurality of pattern elements having pattern element values, the pattern elements including a set of pattern elements that have pattern element values representing message elements of the message, the values of the set of pattern elements having been set to represent the message elements such that the digital authentication pattern'"'"'s usefulness in determining the copying relationship remains substantially unchanged, and the method comprising:

selecting the set of the pattern elements whose pattern element values represent message elements of the message; and

for each pattern element belonging to the selected set, comparing the pattern element with equivalent pattern elements that have a possible message element value to determine the message element values of the message elements in the selected set.

23. The method according to claim 22 further comprising:

after the message has been read, creating an equivalent digital authentication pattern to the digital authentication pattern that contains the message, whereby the digital authentication pattern that contains the message is comparable with the equivalent digital authentication pattern to determine the copying relationship with regard to a digital representation that contains the digital authentication pattern that contains the message.

24. The method according to claim 23 wherein:

in the step of creating, the equivalent digital authentication pattern is created by replacing of pattern elements in the equivalent digital authentication pattern that belong to the selected set with equivalent sets of pattern elements that represent the message elements.

25. The method according to claim 22, wherein:

the message element value belong to a range thereof; and

the equivalent pattern elements include a pattern element for each of the values in the range thereof.

26. The method according to claim 25 wherein:

the pattern elements belong to categories thereof;

the category of a pattern elements indicates the value of the message element represented by the pattern element, and the equivalent pattern elements include a pattern element for each of the categories.

27. The method according to claim 26, wherein:

the pattern element values that represent message elements belong to two categories.

28. The method according to claim 27, wherein:

one of the categories is represented in the pattern element value by inverting the pattern element'"'"'s value.

29. The method according to claim 22 wherein:

the selection of the set of pattern elements is done using a key.

30. The method according to claim 22, wherein:

a message element is repeated in a plurality of sets of pattern elements and further comprising;

for each of the pattern elements that represents the repeated message element, comparing the pattern element that represent the repeated message element with candidate pattern elements that represent each of the possible values of the message element to determine a score with regard to the pattern element for each candidate pattern element;

accumulating for each possible value of the message element, scores for each of the pattern elements that represents the repeated message elements; and

using the accumulated scores to determine the value of the repeated message element.

31. A storage device characterized in that:

the storage device contains code which, when executed by a processor, implements the method according to claim 22.