Encoding and Decoding Signals for Digital Watermarking

• US 20070110272A1
• Filed: 05/16/2006
• Published: 05/17/2007
• Est. Priority Date: 04/25/2001
• Status: Active Grant

• Current Assignee: Digimarc Corporation
• Original Assignee: Digimarc Corporation
• Inventors: Stach, John, Sharma, Ravi
• Granted Patent: US 7,489,801 B2
• Time in Patent Office: Days
• US Class Current: 382/100
• CPC Class Codes: G06T 1/0064 Geometric transfor invariant watermarking, e.g. affine transform invariant
• CPC Class Codes: G06T 2201/0052 Embedding of the watermark in the frequency domain

Abstract

This disclosure describes methods and systems for encoding a digital watermark into and/or detecting a digital watermark from a host (or media) signal such as audio, video or imagery. One implementation involves a method of detecting a digital watermark. The method includes: receiving a host signal carrying a digital watermark; computing attributes of the host signal; using the attributes of the host signal to compute a key; and using the key to detect the digital watermark in a transform domain dependent on the key. Other methods, systems and apparatus are provided as well.

Claims

1. A method comprising:

obtaining a media signal;

computing a reduced-bit representation of the media signal;

influencing a digital watermark embedding process with the reduced-bit representation of the media signal; and

embedding a digital watermark in the media signal with the influenced digital watermark embedding process.

2. The method of claim 1 wherein the media signal represents at least one of audio, video or imagery.

3. The method of claim 1 wherein the watermark embedding process embeds at least a reference signal in the media signal that is used to correct for geometric distortion.

4. The method of claim 3 wherein the reduced-bit representation is used to generate the reference signal.

5. The method of claim 4 wherein the reduced-bit number seeds a pseudorandom number generator used to generate the reference signal.

6. The method of claim 1 wherein the watermark embedding process embeds at least one digital watermark component in a transform domain that is dependent on the reduced-bit representation.

7. The method of claim 1 wherein the reduced-bit representation is used to generate a watermark embedding key associated with a transform domain.

8. The method of claim 1 wherein the reduced-bit representation comprises a hash derived from the media signal.

9. A method comprising:

receiving a media signal comprising a digital watermark hidden therein;

computing a reduced-bit representation of the media signal;

influencing detection of a digital watermark detector with the reduced-bit representation of the media signal; and

analyzing the media signal to detect the digital watermark hidden therein with the influenced digital watermark detector.

10. The method of claim 9 wherein the digital watermark comprises a reference signal, and wherein the reduced-bit representation is associated with detecting the reference signal.

11. The method of claim 10 wherein the reference signal is used to correct for geometric distortion.

12. The method of claim 9 wherein the digital watermark comprises at least one component that is detectable in a transform domain, and wherein the transform domain is associated with the reduced-bit representation.

13. The method of claim 9 wherein the reduced-bit representation is used to calculate a detection key used by the digital watermark detector to detect the digital watermark.

14. The method of claim 9 wherein the reduced-bit representation seeds a pseudorandom number generator used at least in part in detecting the digital watermark.

15. The method of claim 9 wherein the reduced-bit representation comprises a hash derived from the media signal.

16. The method of claim 9 wherein the act of directing detection of a digital watermark detector with the reduced-bit representation of the media signal comprises at least an act of utilizing a transform domain that is associated with the reduced-bit representation of the media signal.

17. A method of detecting a digital watermark comprising:

receiving a host signal carrying a digital watermark;

computing attributes of the host signal;

using the attributes of the host signal to compute a key; and

using the key to detect the digital watermark in a transform domain dependent on the key.

18. The method of claim 17 wherein the host signal comprises at least one of audio, video or imagery.

19. The method of claim 17 wherein the digital watermark comprises at least a reference signal that is used to correct for geometric distortion.

20. The method of claim 17 wherein the attributes seed a pseudo-random number generator used to compute the key.