Z-transform implementation of digital watermarks

• US 6,078,664 A
• Filed: 12/20/1996
• Issued: 06/20/2000
• Est. Priority Date: 12/20/1996
• Status: Expired due to Term

• Current Assignee: Wistaria Trading Inc.
• Original Assignee: Wistaria Trading Inc.
• Inventors: Cooperman, Marc S., Moskowitz, Scott A.
• Primary Examiner(s): Swann, Tod R.
• Assistant Examiner(s): CODDINGTON, TREVOR Q
• Application Number:
  US08/772,222
• Time in Patent Office: 1,278 Days
• Field of Search: 380/28, 380/42, 380/4, 708/5, 708/400
• US Class Current: 380/28
• 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 applying digital watermark data to a content signal comprising:

receiving a content signal;

using z-transform calculations to identify non-deterministic components of said content signal; and

encoding carrier signal independent data into said identified non-deterministic components of said content signal to create a digital sample stream.

2. The method according to claim 1, wherein said carrier signal independent data comprises said digital watermark data.

3. The method according to claim 1, wherein location and parameters of the carrier signal independent data being encoded vary based on a position of a watermarking party in a distribution chain and based on what type and how much information said watermarking party needs to encode.

17. The method of claim 2, wherein said step of encoding carrier signal independent data to a digital sample stream comprises encoding digital watermarks at varying locations in a sample stream with varying envelope parameters, wherein said envelope parameters are stochastically adjusted to optimize said encoding.

19. The method of claim 1, wherein said z-transform calculations represents a recursive digital filter.

4. A method of removing digital watermark data from a digital sample stream, comprising:

receiving a digital sample stream encoded with carrier signal independent data;

using z-transform calculations to identify non-deterministic components of said content signal and

decoding carrier signal independent data from said digital sample stream.

5. The method according to claim 4, wherein said carrier signal independent data comprises digital watermark data.

6. The method according to claim 4, wherein the step of decoding comprises:

decoding carrier signal independent data based a one or more locations within said identified non-deterministic components.

20. The method of claim 4, wherein said z-transform calculations represents a recursive digital filter.

7. A method of analyzing deterministic and non-deterministic components of a signal comprising

receiving a content signal comprising a digital sample stream;

using z-transform calculations to identify deterministic and non-deterministic components of said content signal; and

encoding carrier signal independent data such that it is concentrated primarily in the non-deterministic signal components of the carrier signal,

wherein said non-deterministic signal components comprise at least one of;

a discrete series of digital samples; and

a discrete series of carrier frequency sub-bands of the carrier signal.

8. The method according to claim 7, wherein said carrier signal independent data comprises digital watermark data.

9. The method according to claim 7, wherein the step of encoding carrier signal independent data comprises:

encoding carrier signal independent data such that it is concentrated primarily in the non-deterministic signal components of the carrier signal and such that it is located within the non-deterministic signal components based on a position of a watermarking party in a distribution chain and what type and how much information that party needs to encode.

10. A method of using z-transform calculations to measure a desirability of particular locations in a sample stream in which to encode carrier signal independent data, comprising;

receiving an sample stream; and

using z-transforms to identify locations in said sample stream which would be desirable for encoding carrier signal independent data.

11. The method according to claim 10, further comprising:

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

12. The method according to claim 11,

wherein said carrier signal independent data comprises digital watermark data.

13. The method according to claim 11, further comprising the step of performing an inverse z-transform upon said embedded sample steam to produce an estimated sample series.

14. The method according to claim 13, further comprising the step of computing error data representative of a difference between the estimated sample series and said embedded sample stream.

15. The method according to claim 14, wherein said computed error data is maximized by adjusting the locations of the sample stream wherein the carrier signal independent data are encoded.

16. The method according to claim 14, wherein the locations of the sample stream are selected in order to maximize a difference between the estimated sample series and the embedded sample stream.

18. A method for applying digital watermark data to a coment signal, comprising:

receiving a content signal;

creating a interim signal, said interim signal representing said content signal;

using z-transforms to identify locations in said interim signal which are desirable for encoding of carrier signal independent data;

encoding said carrier signal independent data into said interim signal at said identified locations to create an encoded interim signal;

using an inverse z-transform on said encoded interim signal to create an estimated signal;

determining a difference between said encoded interim signal and said estimated signal;

choosing final locations within said content signal wherein said carrier signal independent data may be embedded to maximize the difference between said encoded interim signal and said estimated signal; and

encoding said content signal with carrier signal independent data at said final locations.