Digital watermark systems and methods

• US 7,987,370 B2
• Filed: 11/14/2007
• Issued: 07/26/2011
• Est. Priority Date: 02/20/1997
• Status: Expired due to Fees

• Current Assignee: Digimarc Corporation
• Original Assignee: Digimarc Corporation
• Inventors: Johnson, Andrew, Biggar, Michael
• Primary Examiner(s): Moazzami; Nasser
• Assistant Examiner(s): Louie; Oscar A
• Application Number:
  US11/940,017
• Publication Number:
  US 20080065896A1
• Time in Patent Office: 1,350 Days
• Field of Search: None
• US Class Current: 713/176
• CPC Class Codes: G06T 1/0021 Image watermarking
• CPC Class Codes: G06T 1/005 Robust watermarking, e.g. average attack or collusion attack resistant
• 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 2201/0083 whereby only watermarked image required at decoder, e.g. source-based, blind, oblivious
• 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 1/32165 using cosine transforms
• CPC Class Codes: H04N 1/32176 using Walsh, Hadamard or Walsh-Hadamard 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 19/00 Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
• 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 21/8358 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

Abstract

A digital watermark is added to audio or visual content. An illustrative embodiment segments the content, permutes the segments, and transforms such data into another domain. The transformed data is altered slightly to encode a watermark. The altered data can then be inverse-transformed, and inverse-permuted, to return same to substantially its original form. Related watermark decoding methods are also detailed, as are ancillary features and techniques.

Claims

1. A digital watermarking method comprising:

receiving coefficients in a transform domain representation;

inserting digital watermark data by altering at least one of the coefficients in accordance with digital watermark data to be encoded;

inverse-transforming the at least one altered coefficients; and

applying an inverse spectral whitening operation to results of the inverse-transforming act, to yield digitally watermarked content;

wherein the foregoing acts are performed by programmable computer circuitry.

2. The method of claim 1, further comprising:

receiving audio or video data;

arranging the audio or video data into one or more data blocks;

applying an inverse spectral whitening operation on the one or more data blocks; and

transforming the scrambled data to yield the coefficients in the transform domain representation, wherein the transforming comprises transforming with a transform selected from the group consisting of a Walsh Hadamard Transform, a Haar Transform, a Discrete Cosine Transform, a Discrete Sine Transform, or a Fast Fourier Transform.

3. A system comprising computer circuitry programmed to watermark content information by performing acts comprising:

receiving coefficients in a transform domain representation;

inserting digital watermark data by altering at least one of the coefficients in accordance with digital watermark data to be encoded;

inverse-transforming said at least one altered coefficients; and

applying an inverse spectral whitening operation to results of the inverse-transform act, to yield digitally watermarked content.

4. The system of claim 3 wherein the computer circuitry is further programmed to perform acts comprising:

receiving audio or video data;

arranging the audio or video data into one or more data blocks;

applying an inverse spectral whitening operation on the one or more data blocks; and

transforming the scrambled data to yield the coefficients in the transform domain representation, wherein the transform comprises a transform selected from the group consisting of a Walsh Hadamard Transform, a Haar Transform, a Discrete Cosine Transform, a Discrete Sine Transform, or a Fast Fourier Transform.

5. A system comprising computer circuitry that is programmed to insert identification or authentication data into digital media data by performing acts comprising:

segmenting the digital media data into data blocks;

applying a pseudo-random reversible function to a block of the digital media data to obtain a modified data block;

applying an orthogonal transform on the modified data block to obtain transform domain data;

modifying at least one selected transform domain data coefficient in accordance with identification or authentication data;

inverse-transforming the transform domain data having the at least one modified coefficient; and

applying an inverse pseudo-random function to obtain watermarked digital media data.

6. A system as claimed in claim 5, wherein the pseudo-random function applied to the data block is a keyed function controlled by a cryptographic key.

7. A system as claimed in claim 5, wherein the pseudo-random function applied to the data block has a property of flattening the power spectral density of the data block.

8. A system as claimed in claim 5, wherein the at least one transform domain data coefficient selected for modification is selected according to a keyed pseudo-random operation.

9. A system as claimed in claim 5, wherein a plurality of data blocks of the digital media data are modified according to the identification or authentication data.

10. A system as claimed in claim 5, wherein the digital media data comprises video data.

11. A system as claimed in claim 5, wherein the digital media data comprises audio data.

12. A system as claimed in claim 5, wherein at least one coefficient in the transform domain data which represents the average (dc) of the data block is restricted from selection for modification with the identification or authentication data.

13. A system as claimed in claim 5, wherein the orthogonal transform comprises a Walsh Hadamard transform.

14. A system as claimed in claim 5, wherein the orthogonal transform comprises a transform selected from a discrete cosine transform, a discrete sine transform and a fast Fourier transform.

15. A system as claimed in claim 5, wherein the pseudo-random reversible function is a permutation of the data block based on a keyed pseudo-random number generator.

16. A system as claimed in claim 5, wherein the computer circuitry is further programmed to determine an average of data values in the data block, subtract the average value from the data values in the data block before applying the pseudo-random function, and add the average value back to the data values in the data block after applying the inverse pseudo-random function.

17. A system comprising circuitry that is programmed to extract identification or authentication data from watermarked digital media data by performing acts comprising:

segmenting the watermarked digital media data into data blocks;

applying a pseudo-random reversible function to a block of the watermarked digital media data to obtain a modified data block;

applying an orthogonal transform to the modified data block to obtain transform domain data; and

extracting identification or authentication data from at least one coefficient of the transform domain data.

18. A system as claimed in claim 17, wherein the pseudo-random function applied to the data block is a keyed function controlled by a cryptographic key.

19. A system as claimed in claim 17, wherein the pseudo-random function applied to the data block has a property of flattening the power spectral density of the data block.

20. A system as claimed in claim 17, wherein the computer circuitry is programmed to select at least one transform domain data coefficient from which to extract identification or authentication data according to a keyed pseudo-random operation.

21. A system as claimed in claim 17, wherein the digital media data comprises video data.

22. A system as claimed in claim 17, wherein the digital media data comprises audio data.

23. A system as claimed in claim 17, wherein the orthogonal transform comprises a Walsh Hadamard transform.

24. A system as claimed in claim 17, wherein the orthogonal transform comprises a transform selected from a discrete cosine transform, a discrete sine transform and a fast Fourier transform.

25. A system as claimed in claim 17, wherein the pseudo-random reversible function is a permutation of the data block based on a keyed pseudo-random number generator.

26. A system as claimed in claim 17, wherein the computer circuitry is further programmed to determine an average of data values in the data block, and subtract the average value from the data values in the data block before applying the pseudorandom function.

27. A system comprising circuitry that is programmed to steganographically encode content data to encode a digital watermark therein, by performing acts comprising:

segmenting the content data into portions, each portion including plural samples, each sample having a value; and

processing at least one of the portions to encode digital watermark data therein;

wherein said circuitry is programmed to subtract from each sample in said at least one of the portions a non-zero value, the same value being subtracted from each sample in said portion.

28. The system of claim 27 wherein the circuitry is programmed to determine an average value of samples within a portion, and subtract said average value from each of the samples included in said portion.

29. The system of claim 27 wherein the samples in each portion have an order, and the circuitry is programmed to scramble said order as part of said process.

30. A system comprising circuitry that is programmed to steganographically encode content data to encode a digital watermark therein, by performing acts comprising:

segmenting the content data into portions, each portion including plural samples, each sample having a value; and

process at least one of the portions to encode digital watermark data therein;

wherein the samples in each portion have an order, and the circuitry is programmed to scramble the order as a part of the process; and

wherein the circuitry is programmed to apply a first reversible spectral whitening operation on a first portion in a first manner, and to apply a second reversible spectral whitening operation on a second portion in a second manner.

31. The system of claim 30 wherein the circuitry is programmed to, after scrambling the order, transform the scrambled samples into an orthogonal domain, and thereafter change the transformed data in accordance with a watermark payload.

32. A system comprising circuitry that is programmed to steganographically encode content data to encode a digital watermark payload therein, by performing acts comprising:

examining orthogonal transform domain coefficients that represent at least part of the content data, each of the examined coefficients being associated with a bit of the watermark payload;

determining whether each of the examined coefficients has an original value consistent associated with a bit of the watermark payload associated therewith; and

if not, change the coefficient value, and else leave the coefficient value unchanged.

33. The system of claim 32 wherein a bit of the watermark payload is represented by a sign of a coefficient associated therewith, and the circuitry is programmed to change the value of the coefficient only if its sign is not in accordance with a value of the watermark payload bit.