Wavelet domain watermarks

• US 20040105569A1
• Filed: 07/24/2003
• Published: 06/03/2004
• Est. Priority Date: 02/14/2000
• Status: Active Grant

• Current Assignee: Digimarc Corporation
• Original Assignee: Adnan M. Alattar, Farid Ahmed, Geoffrey B. Rhoads, Ravi K. Sharma
• Inventors: Ahmed, Farid, Alattar, Adnan M, Sharma, Ravi K., Rhoads, Geoffrey B.
• Granted Patent: US 7,319,775 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
• CPC Class Codes: H04H 20/31 using in-band signals, e.g. subsonic or cue signal
• CPC Class Codes: H04N 1/32154 Transform domain methods H04N1/32309 takes precedence
• CPC Class Codes: H04N 1/3217 using wavelet transforms
• CPC Class Codes: H04N 1/32192 according to calculated or estimated visibility of the additional information in the image
• CPC Class Codes: H04N 1/32203 Spatial or amplitude domain methods H04N1/32309 takes precedence
• 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 2201/3233 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 2201/3281 Encryption; Ciphering
• CPC Class Codes: H04N 2201/3284 for error correction
• CPC Class Codes: H04N 7/163 by receiver means only

Abstract

A wavelet domain watermark encoder and decoder embed and detect auxiliary signals (1300, 1302) in a media signal (1306), such as a still image, video or audio signal. A watermark orientation signal (1302) is embedded in a wavelet decomposed signal (1304) to facilitate detection of the watermark in a geometrically distorted version of the embedded signal.

Claims

1. A method of encoding an auxiliary signal in a media signal comprising:

performing a wavelet decomposition of the media signal into two or more levels of resolution, including an approximate level and one or more higher resolution levels;

modifying the approximate level to encode an auxiliary signal such that the modification is substantially imperceptible in an output form of the media signal.

2. The method of claim 1 wherein the auxiliary signal comprises a watermark orientation signal.

3. The method of claim 2 wherein the watermark orientation signal forms a predetermined pattern in a frequency domain.

4. The method of claim 3 wherein the orientation watermark signal comprises a set of impulse functions in the frequency domain.

5. The method of claim 2 wherein the auxiliary signal carries a message including one or more symbols.

6. The method of claim 5 wherein the orientation signal has attributes for determining orientation of the watermark signal and attributes for carrying the message.

7. The method of claim 2 wherein the media signal is an image signal and the orientation watermark signal is used to determine at least one orientation parameter describing orientation of the auxiliary signal in the image.

8. The method of claim 3 wherein the orientation parameter is a rotation angle.

9. A computer readable medium having software for performing the method of claim 1.

10. A method of detecting an auxiliary signal embedded in a media signal, where the auxiliary information is substantially imperceptible in an output form of the media signal;

the method comprising;

performing a wavelet decomposition of the media signal into two or more levels of resolution, including an approximate level and one or more higher resolution levels; and

detecting the auxiliary information from the approximate level.

11. The method of claim 10 wherein the auxiliary signal comprises a watermark orientation signal;

and further including;

using the orientation signal to determine orientation of the auxiliary signal in the media signal.

12. The method of claim 11 wherein the orientation signal forms a predetermined pattern in a frequency domain.

13. The method of claim 12 wherein the predetermined pattern comprises a set of impulse functions in the frequency domain, the impulse functions having pseudorandom phase.

14. The method of claim 11 including:

performing correlation between a reference orientation signal and the approximate level of the media signal to determine orientation of the auxiliary signal.

15. The method of claim 14 including:

performing a log re-sampling of the approximate level; and

performing the correlation on the re-sampled media signal and log sampled version of the reference orientation signal.

16. The method of claim 14 including:

performing a polar re-sampling of the approximate level; and

performing the correlation on the re-sampled media signal and polar sampled version of the reference orientation signal.

17. A computer readable medium having software for performing the method of claim 10.

18. A method of embedding an auxiliary signal into a media signal so that the auxiliary signal is substantially imperceptible to a human in the embedded media signal, the method comprising:

performing a wavelet decomposition of the media signal; and

embedding a watermark orientation signal into the wavelet decomposition, wherein the auxiliary signal includes the watermark orientation signal and the watermark orientation signal has attributes used to determine orientation of the auxiliary signal in a geometrically distorted version of the media signal.

19. The method of claim 18 wherein the auxiliary signal carries a message of one or more symbols.

20. The method of claim 19 wherein the watermark orientation signal carries the message.

21. The method of claim 18 wherein the watermark orientation signal forms a predetermined pattern in a frequency domain.

22. The method of claim 21 wherein the watermark orientation signal comprises a set of impulse functions with random phase in the frequency domain.

23. A computer readable medium having software for performing the method of claim 18.

24. A method of detecting an auxiliary signal embedded in a media signal, where the auxiliary signal is substantially imperceptible in an output form of the media signal;

the method comprising;

performing a wavelet decomposition of the media signal into two or more levels of resolution; and

correlating a reference watermark orientation signal with the wavelet decomposition of the media signal to determine orientation of the auxiliary signal in the media signal.

25. The method of claim 24 including:

performing multi-level correlation between the reference watermark orientation signal and the wavelet decomposition.

26. The method of claim 25 including:

performing correlation at an initial low level of resolution of the wavelet decomposition; and

refining results of the correlation at least one higher level of resolution of the wavelet decomposition.

27. The method of claim 24 including:

performing correlation at subbands within a level of resolution of the wavelet decomposition;

and combining results of the correlations at the subbands.

28. The method of claim 24 including:

performing a polar resampling of at least one level of resolution; and

performing correlation on the resampled level of correlation.

29. A computer readable medium including software for performing the method of claim 24.