Watermark embedder and reader

• US 6,718,047 B2
• Filed: 08/07/2002
• Issued: 04/06/2004
• Est. Priority Date: 05/08/1995
• Status: Expired due to Fees

• Current Assignee: Digimarc Corporation
• Original Assignee: Digimarc Corporation
• Inventors: Rhoads, Geoffrey B.
• Primary Examiner(s): Couso, Jose L.
• Application Number:
  US10/215,389
• Publication Number:
  US 20030053653A1
• Time in Patent Office: 608 Days
• Field of Search: 382/100, 382/232, 382/284, 395/135, 358/124, 358/142, 358/448, 358/450, 358/454, 380/4, 380/23, 380/25, 380/54, 380/231-234, 380/287, 283/6, 283/93, 283/94, 283/72, 283/73, 283/113, 283/901, 348/475, 235/494, 713/176, 705/1, 705/44
• US Class Current: 382/100
• CPC Class Codes: B42D 25/00 Information-bearing cards or sheet-like structures characterised by identification or security features; Manufacture thereof printing processes to produce identification or security features B41M3/14
• CPC Class Codes: B42D 25/333 Watermarks
• CPC Class Codes: G06F 16/955 using information identifiers, e.g. uniform resource locators [URL]
• CPC Class Codes: G06K 19/06037 multi-dimensional coding
• CPC Class Codes: G06K 19/06046 Constructional details
• CPC Class Codes: G06K 19/14 the marking being sensed by radiation
• CPC Class Codes: G06K 19/18 Constructional details
• CPC Class Codes: G06K 2019/06253 for a specific application
• CPC Class Codes: G06K 7/1417 2D bar codes
• CPC Class Codes: G06K 7/1447 extracting optical codes from image or text carrying said optical code
• CPC Class Codes: G06Q 20/1235 with control of digital rights management [DRM]
• CPC Class Codes: G06Q 20/341 Active cards, i.e. cards including their own processing means, e.g. including an IC or chip
• CPC Class Codes: G06Q 20/40145 Biometric identity checks
• CPC Class Codes: G06T 1/0028 Adaptive watermarking, e.g. Human Visual System [HVS]-based watermarking
• CPC Class Codes: G06T 1/005 Robust watermarking, e.g. average attack or collusion attack resistant
• CPC Class Codes: G06T 1/0064 Geometric transfor invariant watermarking, e.g. affine transform invariant
• CPC Class Codes: G06T 1/0071 using multiple or alternating watermarks
• CPC Class Codes: G06T 2201/0051 Embedding of the watermark in the spatial domain
• CPC Class Codes: G06T 2201/0052 Embedding of the watermark in the frequency domain
• CPC Class Codes: G06T 2201/0061 Embedding of the watermark in each block of the image, e.g. segmented watermarking
• CPC Class Codes: G06T 2201/0064 : for copy protection or copy management, e.g. CGMS, copy only once, one-time copy
• CPC Class Codes: G06T 2201/0065 : Extraction of an embedded watermark; Reliable detection
• CPC Class Codes: G06V 30/40 : Document-oriented image-based pattern recognition
• CPC Class Codes: G07C 9/253 : visually
• CPC Class Codes: G07D 7/0034 : using watermarks
• CPC Class Codes: G07D 7/004 : using digital security elements, e.g. information coded on a magnetic thread or strip
• CPC Class Codes: G07F 7/086 : by passive credit-cards adapted therefor, e.g. constructive particularities to avoid counterfeiting, e.g. by inclusion of a physical or chemical security-layer for security documents G07D7/00; for the reading of record-carriers in general G06K7/00; for the design of coded credit-cards G06K19/10
• CPC Class Codes: G07F 7/1008 : Active credit-cards provided with means to personalise their use, e.g. with PIN-introduction/comparison system
• CPC Class Codes: G10L 19/018 : Audio watermarking, i.e. embedding inaudible data in the audio signal
• CPC Class Codes: G11B 20/00086 : Circuits for prevention of unauthorised reproduction or copying, e.g. piracy indicating unauthorised use of record carriers in general G11B23/28; scrambling for television signal recording H04N5/913; network architectures or network protocols for network security H04L63/00; cryptographic mechanisms or cryptographic arrangements for secret or secure communication H04L9/00
• CPC Class Codes: G11B 20/00884 : involving a watermark, i.e. a barely perceptible transformation of the original data which can nevertheless be recognised by an algorithm
• CPC Class Codes: G11B 20/00891 : embedded in audio data
• CPC Class Codes: H04H 20/31 : using in-band signals, e.g. subsonic or cue signal
• CPC Class Codes: H04L 63/06 : for supporting key management in a packet data network cryptographic mechanisms or cryptographic arrangements for key management H04L9/08
• CPC Class Codes: H04N 1/00005 : relating to image data
• CPC Class Codes: H04N 1/00037 : Detecting, i.e. determining the occurrence of a predetermined state H04N1/00031 takes precedence
• CPC Class Codes: H04N 1/00079 : remotely
• CPC Class Codes: H04N 1/32122 : in a separate device, e.g. in a memory or on a display separate from image data
• CPC Class Codes: H04N 1/32144 : embedded in the image data, i.e. enclosed or integrated in the image, e.g. watermark, super-imposed logo or stamp
• CPC Class Codes: H04N 1/32149 : Methods relating to embedding, encoding, decoding, detection or retrieval operations
• CPC Class Codes: H04N 1/32154 : Transform domain methods H04N1/32309 takes precedence
• CPC Class Codes: H04N 1/3216 : using Fourier transforms
• CPC Class Codes: H04N 1/32187 : with selective or adaptive application of the additional information, e.g. in selected frequency coefficients
• CPC Class Codes: H04N 1/32203 : Spatial or amplitude domain methods H04N1/32309 takes precedence
• CPC Class Codes: H04N 1/32208 : involving changing the magnitude of selected pixels, e.g. overlay of information or super-imposition H04N1/32219, H04N1/32224 take precedence
• CPC Class Codes: H04N 1/32229 : with selective or adaptive application of the additional information, e.g. in selected regions of the image H04N1/32213 takes precedence
• CPC Class Codes: H04N 1/32251 : in multilevel data, e.g. greyscale or continuous tone data
• CPC Class Codes: H04N 1/32288 : Multiple embedding, e.g. cocktail embedding, or redundant embedding, e.g. repeating the additional information at a plurality of locations in the image
• CPC Class Codes: H04N 1/32352 : Controlling detectability or arrangements to facilitate detection or retrieval of the embedded information, e.g. using markers for decoding, detection or retrieval operations H04N1/32149 and subgroups take precedence
• CPC Class Codes: H04N 19/467 : characterised by the embedded information being invisible, e.g. watermarking
• CPC Class Codes: H04N 19/645 : by grouping of coefficients into blocks after the transform
• CPC Class Codes: H04N 21/23892 : involving embedding information at multiplex stream level, e.g. embedding a watermark at packet level
• CPC Class Codes: H04N 21/44008 : involving operations for analysing video streams, e.g. detecting features or characteristics in the video stream arrangements characterised by components specially adapted for monitoring, identification or recognition of video in broadcast systems H04H60/59
• CPC Class Codes: H04N 21/4627 : Rights management associated to the content security in data switching network management H04L41/28; security management or policies for network security H04L63/20; access security in wireless networks H04W12/08
• CPC Class Codes: H04N 21/8358 : involving watermark protecting executable software by watermarking G06F21/16; image watermarking in general G06T1/0021; watermarks inserted in still images for transmission purposes H04N1/32144; inserting watermarks during video coding H04N19/467
• CPC Class Codes: H04N 2201/3205 : of identification information, e.g. name or ID code H04N2201/3209 takes precedence
• CPC Class Codes: H04N 2201/3207 : of an address
• CPC Class Codes: H04N 2201/3225 : of data relating to an image, a page or a document
• CPC Class Codes: H04N 2201/3226 : of identification information or the like, e.g. ID code, index, title, part of an image, reduced-size image
• CPC Class Codes: H04N 2201/323 : for tracing or tracking, e.g. forensic tracing of unauthorized copies
• CPC Class Codes: H04N 2201/3233 : of authentication information, e.g. digital signature, watermark
• CPC Class Codes: H04N 2201/327 : which are undetectable to the naked eye, e.g. embedded codes
• CPC Class Codes: H04N 2201/3271 : Printing or stamping
• CPC Class Codes: H04N 2201/3274 : Storage or retrieval of prestored additional information
• CPC Class Codes: H04N 2201/328 : Processing of the additional information
• CPC Class Codes: H04N 2201/3284 : for error correction
• CPC Class Codes: H04N 7/163 : by receiver means only

Abstract

A watermark system includes an embedder, detector, and reader. The watermark embedder encodes a watermark signal in a host signal to create a combined signal. The detector looks for the watermark signal in a potentially corrupted version of the combined signal, and computes its orientation. Finally, a reader extracts a message in the watermark signal from the combined signal using the orientation to approximate the original state of the combined signal. While adapted for images, video and audio, the watermark system applies to other electronic and physical media. For example, it can be applied to mark graphical models, blank paper, film and other substrates, texturing objects for ID purposes, etc.

Claims

1. A digital watermark embedded in an electronic or physical media signal, comprising two or more components, at least one of the components being encoded more redundantly than another component, wherein the watermark is embedded in the media signal using a method, comprising:

deriving a first gain corresponding to elements in the media signal that varies as a function of data hiding potential of the media signal;

deriving a second gain that varies as a function of auxiliary message elements of the digital watermark to be embedded and corresponding elements of the media signal;

using the first and second gains to control signal energy of a digital watermark signal carrying the auxiliary message elements in a watermarked version of the media signal such that the digital watermark is substantially imperceptible in the watermarked media signal, yet automatically detectable in the watermarked media signal without reference to the media signal.

2. The digital watermark of claim 1, wherein the watermark is embedded using a user adjustable gain in addition to the first and second gains to control signal energy of the digital watermark.

3. The digital watermark of claim 1 wherein the media signal is an image signal and the first gain is a function of luminance of the image signal.

6. The digital watermark of claim 1 wherein the media signal comprises an image signal and the auxiliary message elements correspond to a modulated carrier signal, where the carrier signal is a function of a key.

7. The digital watermark of claim 6 wherein the modulated carrier signal is generated by modulating a carrier signal with a plural bit message to be embedded in the media signal.

8. The digital watermark of claim 7 wherein the modulated carrier signal is a function of a pseudo random number.

9. The digital watermark of claim 7 wherein the plural bit message is an error correction encoded message.

10. The digital watermark of claim 1 wherein the second gain is computed at least in part by evaluating characteristics of elements of the media signal to determine whether variations in the characteristics of the elements of the media signal are consistent with variations to the media signal associated with embedding corresponding auxiliary message elements;

and deriving the second gain as a function of an extent to which the variations of characteristics of the elements of the media signal are consistent with variations to the media signal associated with embedding the corresponding auxiliary message elements.

11. The digital watermark of claim 10 wherein the auxiliary message elements are computed by modulating a plural bit message with a carrier signal.

12. The digital watermark of claim 11 wherein the carrier signal is generated as a function of a key.

13. The digital watermark of claim 12 wherein the carrier signal comprises a pseudorandom carrier signal.

14. The digital watermark of claim 1 wherein the components are sets of binary numbers in a multibit watermark message, the message being error correction coded such that at least one set of binary numbers is encoded more redundantly than another set.

15. The digital watermark of claim 1 wherein the components include components in different transform domains.

16. The digital watermark of claim 15 wherein one of the transform domains is a spatial domain and another is a spatial frequency domain.

17. The digital watermark of claim 1 wherein one of the components carries a message, and another component acts as orientation signal used to identify a location of the watermark in the media.

18. The digital watermark of claim 1 wherein one of the components carries a message payload and is used in locating the watermark in the media.

19. The digital watermark of claim 1 wherein at least one of the components is more redundant in a spatial domain than another component.

20. The watermark of claim 1 wherein at lease one of the components is more redundant in a spatial frequency domain than another component.

4. The digital watermark of 1 wherein the first gain varies as a function of signal activity around corresponding elements of the media signal.

5. The digital watermark of claim 4 wherein signal activity is measured at least in part by calculating edges in the media signal at corresponding elements of the media signal.

21. A digital watermark embedded in an electronic or physical media, comprising two or more signal components, the signal components being encoded such that each component has a different signal strength, wherein the digital watermark is embedded in the media signal using a method, comprising:

deriving a first gain corresponding to elements in the media signal that varies as a function of data hiding potential of the media signal;

deriving a second gain that varies as a function of auxiliary message elements of the digital watermark to be embedded and corresponding elements of the media signal;

using the first and second gains to control signal energy of a digital watermark signal carrying the auxiliary message elements in a watermarked version of the media signal such that the digital watermark is substantially imperceptible in the watermarked media signal, yet automatically detectable in the watermarked media signal without reference to the media signal.

22. The watermark of claim 21 wherein a gain is applied to each component such that the components have different signal strength.

23. The watermark of claim 21 wherein at least one of the components is encoded more redundantly such that it has greater signal strength than another component.

24. The watermark of claim 22 including at least first and second components, each carrying messages, and the first component carries a shorter message and has a stronger signal strength than the second component.

25. The watermark of claim 24 wherein the first and second components are multibit messages, and one multibit message is encoded more redundantly than the other.

26. The watermark of claim 24 wherein the first and second components are defined in the same transform domain.

27. The watermark of claim 24 wherein the first and second components are defined in different transform domains.

28. A method of embedding a digital watermark in an electronic or physical media signal, the method comprising:

deriving a first gain corresponding to elements in the media signal that varies as a function of data hiding potential of the media signal;

deriving a second gain that varies as a function of auxiliary message elements of the digital watermark to be embedded and corresponding elements of the media signal;

using the first and second gains to control signal energy of a digital watermark signal carrying the auxiliary message elements in a watermarked version of the media signal such that the digital watermark is substantially imperceptible in the watermarked media signal, yet automatically detectable in the watermarked media signal without reference to the media signal.

29. The method of claim 28, wherein the watermark is embedded using a user adjustable gain in addition to the first and second gains to control signal energy of the digital watermark.

30. The method of claim 28 wherein the media signal is an image signal and the first gain is a function of luminance of the image signal.

31. The method of claim 28 wherein the first gain varies as a function of signal activity around corresponding elements of the media signal.

32. The method of claim 31 wherein signal activity is measured at least in part by calculating edges in the media signal at corresponding elements of the media signal.

33. The method of claim 28 wherein the media signal comprises an image signal and the auxiliary message elements correspond to a modulated carrier signal, where the carrier signal is a function of a key.

34. The method of claim 33 wherein the modulated carrier signal is generated by modulating a carrier signal with a plural bit message to be embedded in the media signal.

35. The method of claim 34 wherein the modulated carrier signal is a function of a pseudo random number.

36. The method of claim 34 wherein the plural bit message is an error correction encoded message.

37. The method of claim 28 wherein the second gain is computed at least in part by evaluating characteristics of elements of the media signal to determine whether variations in the characteristics of the elements of the media signal are consistent with variations to the media signal associated with embedding corresponding auxiliary message elements;

and deriving the second gain as a function of an extent to which the variations of characteristics of the elements of the media signal are consistent with variations to the media signal associated with embedding the corresponding auxiliary message elements.

38. The method of claim 37 wherein the auxiliary message elements are computed by modulating a plural bit message with a carrier signal.

39. The method of claim 38 wherein the carrier signal is generated as a function of a key.

40. The method of claim 39 wherein the carrier signal comprises a pseudorandom carrier signal.

41. The method of claim 28 wherein the digital watermark has two more components, and the components are sets of binary numbers in a multibit watermark message, the message being error correction coded such that at least one set of binary numbers is encoded more redundantly than another set.

42. The method of claim 28 wherein the digital watermark has two more components, and the components include components in different transform domains.

43. The method of claim 42 wherein one of the transform domains is a spatial domain and another is a spatial frequency domain.

44. The method of claim 28 wherein the digital watermark has two more components, and one of the components carries a message, and another component acts as orientation signal used to identify a location of the watermark in the media.

45. The method of claim 28 wherein the digital watermark has two more components, and one of the components carries a message payload and is used in locating the watermark in the media.

46. The method of claim 28 wherein the digital watermark has two more components, and at least one of the components is more redundant in a spatial domain than another component.

47. The method of claim 28 wherein the digital watermark has two more components, and at lease one of the components is more redundant in a spatial frequency domain than another component.

55. A tangible storage medium on which is stored an electronic or physical media signal embedded with a digital watermark using the method of claim 28.

57. A tangible storage medium storing instructions for performing the method of claim 28.

48. A method of embedding a digital watermark in electronic or physical media, comprising:

deriving a first gain corresponding to elements in the media signal that varies as a function of data hiding potential of the media signal;

deriving a second gain that varies as a function of auxiliary message elements of the digital watermark to be embedded and corresponding elements of the media signal;

using the first and second gains to control signal energy of a digital watermark signal carrying the auxiliary message elements in a watermarked version of the media signal such that the digital watermark is substantially imperceptible in the watermarked media signal, yet automatically detectable in the watermarked media signal without reference to the media signal.

49. The method of claim 48 wherein the digital watermark has two or more components, and a gain is applied to each component such that the components have different signal strength.

50. The method of claim 48 wherein the digital watermark has two or more components, and at least one of the components is encoded more redundantly such that it has greater signal strength than another component.

51. The method of claim 49 including at least first and second components, each carrying messages, and the first component carries a shorter message and has a stronger signal strength than the second component.

52. The method of claim 51 wherein the first and second components are multibit messages, and one multibit message is encoded more redundantly than the other.

53. The method of claim 51 wherein the first and second components are defined in the same transform domain.

54. The method of claim 51 wherein the first and second components are defined in different transform domains.

56. A tangible storage medium on which is stored an electronic or physical media signal embedded with a digital watermark using the method of claim 48.

58. A tangible storage medium storing instructions for performing the method of claim 48.