Watermarking holograms

• US 20020080992A1
• Filed: 12/21/2000
• Published: 06/27/2002
• Est. Priority Date: 12/21/2000
• Status: Abandoned Application

• Current Assignee: Digimarc Corporation
• Original Assignee: Digimarc Corporation
• Inventors: Brunk, Hugh L., Carr, J. Scott, Decker, Stephen K.
• Application Number:
  US09/741,779
• Publication Number:
  US 20020080992A1
• Time in Patent Office: Days
• US Class Current: 382/100
• CPC Class Codes: G03H 1/0011 for security or authentication holograms on information-bearing cards B42D25/328; testing papers with holograms G07D7/0032
• CPC Class Codes: G03H 1/08 Synthesising holograms, i.e. holograms synthesized from objects or objects from hologramsusing electric digital computers G06F; G06T
• CPC Class Codes: G03H 1/0808 Methods of numerical synthesis, e.g. coherent ray tracing [CRT], diffraction specific
• CPC Class Codes: G06T 1/0021 Image watermarking
• CPC Class Codes: G07D 7/0032 using holograms
• CPC Class Codes: G07D 7/0034 using watermarks
• CPC Class Codes: G07F 7/08 by coded identity card or credit card or other personal identification means without personal verification means G07F7/02
• 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 7/12 Card verification
• CPC Class Codes: H04N 1/00249 with a photographic apparatus, e.g. a photographic printer or a projector photographic apparatus per se G03B, G03D
• CPC Class Codes: H04N 2201/3215 of a time or duration
• CPC Class Codes: H04N 2201/3233 of authentication information, e.g. digital signature, watermark
• CPC Class Codes: H04N 2201/3281 Encryption; Ciphering

Abstract

Methods for integrating digital watermarks into holograms, watermarked hologram structures, and related applications. One method creates a watermark image, and then embeds the watermark image into a holographic structure. The holographic structure is created using computer generated holography to create a digital representation of the holographic structure. This digital representation is recorded on a physical substrate using optical techniques or microlithography. As an alterative, a watermark signal is embedded in a physical holographic structure by embedding the signal into an image that is optically merged with the holographic structure as it is optically recorded, or by embedding the signal into an image or physical model from which the holographic structure is formed. Another approach the creates a halftone watermarked image, and forms the halftone watermarked image in the hologram by creating hologram dots corresponding to the dots in the halftone watermarked image.

Claims

1. A method of embedding a digital watermark in an optically variable device comprising:

creating a watermark image; and

embedding the watermark image into a holographic structure.

2. The method of claim 1 wherein the holographic structure is recorded on a physical medium by optically projecting the holographic structure on a photosensitive material.

3. The method of claim 1 wherein the watermark image comprises an image that as been embedded with a digital watermark.

4. The method of claim 1 wherein the watermark image modulates a 2D or 3D digital image model to create a watermarked image, and the watermarked image is transformed into the holographic structure.

5. The method of claim 1 wherein the watermark image is transformed into the holographic structure.

6. The method of claim 5 wherein the watermark image is optically merged with an interference pattern of a hologram on a photosensitive material.

7. The method of claim 5 wherein the watermark image is integrated into the holographic structure using wavefront calculations to calculate a digital representation of the holographic structure, which is recorded on a physical medium by optically creating a diffraction grating on the physical medium or using microlithography to reproduce the holographic structure on the physical medium.

8. The method of claim 1 wherein creating the watermark image includes:

spread spectrum modulating a binary message to create a watermark signal.

9. The method of claim 8 including:

altering values of a host image to embed the watermark signal in the host image, such that the altered host image forms the watermark image.

10. The method of claim 9 including:

perceptually adapting the watermark signal to the host image such that the watermark signal is imperceptibly embedded in the host image.

11. The method of claim 1 including:

embedding two or more different watermark signal into the holographic structure.

12. The method of claim 11 wherein one of the watermark signals encodes a key to decode another watermark signal.

13. The method of claim 1 wherein the watermark image includes an orientation signal used to re-align image data scanned from the holographic structure before decoding the watermark image.

14. A computer readable medium on which is stored software for creating a digital representation of the holographic structure using the method of claim 1.

15. A watermark decoder for detecting a watermark signal from a digital image captured of a physical representation of the holographic structure of claim 1.

16. A physical holographic structure embedded with a watermark according to the method of claim 1.

17. The holographic structure of claim 16 wherein the watermark is machine readable by executing a watermark decode process on a digital image captured of the holographic structure.

18. The holographic structure of claim 17 wherein the watermark carries a message, including an identifier number.

19. The holographic structure of claim 18 wherein the identifier number comprises a serial number to identify the holographic structure or group of holographic structures.

20. The holographic structure of claim 17 wherein the watermark carries authentication information that is compared with information related to an object bearing the holographic structure to authenticate the object.

21. The holographic structure of claim 20 wherein the information related to the object is on the object in human or machine readable form.

22. The holographic structure of claim 21 wherein the information related to the object is on the object in a machine readable form.

23. The holographic structure of claim 21 wherein the information related to the object is stored in a database record indexed by the message carried in the watermark.

24. The holographic structure of claim 17 wherein the watermark carries a key used to decode an authentication mark on an object bearing the holographic structure.

25. The holographic structure of claim 17 wherein the watermark carries an index to a database record storing information related to an object bearing the holographic structure.

26. The holographic structure of claim 17 wherein the watermark carries a message used to look up a network address of a network resource related to an object bearing the holographic structure.

27. The holographic structure of claim 17 wherein the watermark is encoded so as to be viewable only at selected orientation and focal plane.

29. The method of claim 28 wherein the hologram dots are created by demetalizing a metal layer of the hologram such that remaining metal dots are in the pattern of the halftone watermarked image.

30. The method of claim 28 wherein the hologram dots are created by forming a dot matrix hologram comprised of discrete diffraction grating dots corresponding to the halftone watermarked image.

31. The method of claim 28 wherein the halftone watermarked image is created by altering sample values of a host image.

32. The method of claim 28 including:

spread spectrum modulating a message to create a watermark signal and mapping elements of the watermark signal to discrete location in the halftone image.

33. The method of claim 28 including:

error correction encoding a message and embedding the message in a halftone image to create the halftone watermarked image.

34. A physical holographic structure embedded with a watermark according to the method of claim 28.

35. The holographic structure of claim 34 wherein the watermark is machine readable by executing a watermark decode process on a digital image captured of the holographic structure.

36. The holographic structure of claim 35 wherein the watermark carries a message, including an identifier number.

37. The holographic structure of claim 36 wherein the identifier number comprises a serial number to identify the holographic structure or group of holographic structures.

38. The holographic structure of claim 35 wherein the watermark carries authentication information that is compared with information related to an object bearing the holographic structure to authenticate the object.

39. The holographic structure of claim 38 wherein the information related to the object is on the object in human or machine readable form.

40. The holographic structure of claim 39 wherein the information related to the object is on the object in a machine readable form.

41. The holographic structure of claim 39 wherein the information related to the object is stored in a database record indexed by the message carried in the watermark.

42. The holographic structure of claim 35 wherein the watermark carries a key used to decode an authentication mark on an object bearing the holographic structure.

43. The holographic structure of claim 35 wherein the watermark carries an index to a database record storing information related to an object bearing the holographic structure.

44. The holographic structure of claim 35 wherein the watermark carries a message used to look up a network address of a network resource related to an object bearing the holographic structure.

45. The holographic structure of claim 35 wherein the watermark is encoded so as to be viewable only at selected orientation and focal plane.

47. The reader of claim 46 wherein the decoder is operable to detect the watermark signal from a hologram and control usage of an image scanned from an object bearing the hologram based on the message.

48. The reader of claim 46 wherein the decoder is operable to compare the message with information related to an object bearing the watermarked hologram to authenticate the object.

49. The reader of claim 46 wherein the decoder is operable to establish a connection with a network resource using the message.

50. The reader of claim 49 wherein the network resource is a network server and the decoder is operable to fetch information related to the object from the network server over a computer network.

51. The reader of claim 46 wherein the watermarked hologram carries the watermark signal in a pattern of hologram dots.

52. The reader of claim 46 wherein the watermarked hologram carries the watermark signal in a holographic image that is formed by directing light onto a diffraction grating of the watermarked hologram.

28. A method for integrating a digital watermark into a hologram comprising:

creating a halftone watermarked image; and

forming the halftone watermarked image in the hologram by creating hologram dots corresponding to the dots in the halftone watermarked image.

46. A watermark reader operable to decode a watermark from a watermarked hologram, the decoder comprising:

a watermark decoder for detecting a watermark signal in an image scanned from a watermarked hologram; and

a message decoder for extracting a message from the watermark signal.