Z-transform implementation of digital watermarks

• US 7,152,162 B2
• Filed: 12/30/2004
• Issued: 12/19/2006
• Est. Priority Date: 12/20/1996
• Status: Expired due to Fees

• Current Assignee: Wistaria Trading Inc.
• Original Assignee: Wistaria Trading Inc.
• Inventors: Moskowitz, Scott A., Cooperman, Marc
• Primary Examiner(s): Zand, Kambiz
• Assistant Examiner(s): Lanier, Benjamin E.
• Application Number:
  US11/026,234
• Publication Number:
  US 20050135615A1
• Time in Patent Office: 719 Days
• Field of Search: None
• US Class Current: 713/176
• 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 1/0085 Time domain based watermarking, e.g. watermarks spread over several images
• CPC Class Codes: G06T 2201/0052 Embedding of the watermark in the frequency domain
• CPC Class Codes: H04L 2463/101 applying security measures for digital rights management
• CPC Class Codes: H04L 63/12 Applying verification of the received information cryptographic mechanisms or cryptographic arrangements for data integrity or data verification H04L9/32
• 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 1/32187 with selective or adaptive application of the additional information, e.g. in selected frequency coefficients
• CPC Class Codes: H04N 1/32277 Compression
• CPC Class Codes: H04N 19/467 characterised by the embedded information being invisible, e.g. watermarking
• 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

Z-transform calculations may be used to encode (and/or decode) carrier signal independent data (e.g., digital watermarks) to a digital sample stream. Deterministic and non-deterministic components of a digital sample stream signal may be analyzed for the purposes of encoding carrier signal independent data to the digital sample stream. The carrier signal independent data may be encoded in a manner such that it is restricted or concentrated primarily in the non-deterministic signal components of the carrier signal. The signal components can include a discrete series of digital samples and/or a discreet series of carrier frequency sub-bands of the carrier signal. Z-transform calculations may be used to measure a desirability of particular locations and a sample stream in which to encode the carrier signal independent data.

Claims

1. A method for extracting a digital watermark from a content signal, comprising

a) receiving a content signal;

b) using linear predictive coding calculations to identify predictable and unpredictable components of said content signal, said unpredictable signal components being characterized by at least one of the following groups;

i) a discrete series of digital samples, and

ii) a discrete series of carrier frequency sub-bands of the content signal; and

c) extracting the digital watermark from the unpredictable signal components of the content signal.

2. The method of claim 1, wherein the content signal is an analog waveform.

3. The method of claim 1, where the signal components are non-contiguous.

4. The method of claim 1, where the content signal may first be decompressed before using linear predictive coding to identify signal components.

5. The method of claim 1, where the location of at least a portion of the digital watermark is represented by at least one of the following:

sample, frequency, phase or combinations thereof.

6. The method of claim 1, wherein the step of extracting comprises:

extracting the digital watermark based on one or more locations within said unpredictable signal components.

7. The method of claim 1, wherein the signal components are identified using at least one of the following characteristics of the content signal:

wave, amplitude, frequency, band energy, and phase energy.

8. The method of claim 1, where the linear predictive coding calculations enables compression of the predictable signal components and at least one of the following:

preservation of the unpredictable signal components or stochastic representation of the unpredictable signal components.

9. The method of claim 1, where the digital watermark is accessible with a key.

10. A method for extracting a digital watermark from a content signal, comprising

a) receiving a content signal;

b) using linear predictive coding calculations to identify predictable and unpredictable components of said content signal, said predictable signal components being characterized by at least one of the following group;

i) a discrete series of digital samples, and

ii) a discrete series of carrier frequency sub-bands of the content signal; and

c) extracting the digital watermark from the predictable signal components of the content signal.

11. The method of claim 10, wherein the content signal is an analog waveform.

12. The method of claim 10, where the signal components are non-contiguous.

13. The method of claim 10, where the content signal may first be decompressed before using linear predictive coding to identify signal components.

14. The method of claim 10, where the location of at least a portion of the digital watermark is represented by at least one of the following:

sample, frequency, phase or combinations thereof.

15. The method of claim 10, wherein the step of extracting comprises:

extracting the digital watermark based on one or more locations within said predictable signal components.

16. The method of claim 10, wherein the signal components are identified using at least one of the following characteristics of the content signal:

wave, amplitude, frequency, band energy, and phase energy.

17. The method of claim 10, where the linear predictive coding calculations enables compression of the predictable signal components and at least one of the following:

preservation of the unpredictable signal components or stochastic representation of the unpredictable signal components.

18. A method of using linear predictive coding calculations to measure the desirability of particular locations in a sample stream in which to encode content signal independent data, including a digital watermark, comprising:

receiving a sample stream;

using linear predictive coding calculations to identify locations in said sample stream which would be desirable for encoding content signal independent data; and

encoding said content signal independent data into said identified locations in said sample stream to produce an embedded sample stream.

19. The method of claim 18, where the embedded sample stream is an arbitrarily close approximation of the sample stream.

20. the method of claim 18, where the content signal independent data is accessible with a key.