Digital watermark embedding apparatus, digital watermark detecting apparatus, digital watermark embedding method, digital watermark detecting method and computer program product

• US 20020071593A1
• Filed: 10/30/2001
• Published: 06/13/2002
• Est. Priority Date: 10/31/2000
• Status: Abandoned Application

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Muratani, Hirofumi
• Application Number:
  US09/984,669
• Publication Number:
  US 20020071593A1
• 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 1/0085 Time domain based watermarking, e.g. watermarks spread over several images
• CPC Class Codes: G06T 2201/0061 Embedding of the watermark in each block of the image, e.g. segmented watermarking
• CPC Class Codes: G10L 19/018 Audio watermarking, i.e. embedding inaudible data in the audio signal
• 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 1/32267 combined with processing of 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 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 embedding apparatus for embedding watermark information into a digital content, obtains a predetermined topological invariant corresponding to the watermark information to be embedded into the digital content, and sets the predetermined topological invariant to the digital content by modifying the digital content into which the watermark information is to be embedded.

Claims

1. A digital watermark embedding apparatus for embedding watermark information into a digital content, comprising:

a unit configured to obtain a predetermined topological invariant corresponding to the watermark information to be embedded into the digital content; and

a setting unit configured to set the predetermined topological invariant to the digital content by modifying said digital content into which said watermark information is to be embedded.

2. The digital watermark embedding apparatus according to claim 1, wherein

said setting unit changes a predetermined part of a bit string corresponding to a spatial or time-basis position of the digital content to a target value determined by the position of the bit string and the predetermined topological invariant or a target value restorable value.

3. The digital watermark embedding apparatus according to claim 1, wherein

said setting unit sets a value, allowing a representative value representing a divided region which is obtained by dividing the digital content in a spatial manner or a time-basis manner and obtained from a predetermined part of one or a plurality of bit strings corresponding to a spatial or time-basis position of the divided region to become a target value determined by the spatial or time-basis position of the divided region and the predetermined topological invariant or a target value restorable value, to the predetermined part of the one or the plurality of bit strings.

4. The digital watermark embedding apparatus according to claim 3, wherein

the bit string corresponding to the plurality of positions configures a content of one divided region, and the representative value is an average value of values of the predetermined parts of the plurality of bit strings.

5. The digital watermark embedding apparatus according to claim 2, wherein

said setting unit generates a mapping to a target topological space defined by the predetermined part of said bit string from a base topological space defined by the spatial or time-basis position, and obtains the target value corresponding to the position based on a function for applying the predetermined topological invariant.

6. The digital watermark embedding apparatus according to claim 5, wherein

the function has the predetermined topological invariant as a parameter.

7. The digital watermark embedding apparatus according to claim 5, wherein

the setting unit evaluates an influence on the digital content if the predetermined topological invariant is set to the digital content using a plurality of different functions, and utilizes a function evaluated to minimize the influence on the digital content as the function for applying the predetermined topological invariant.

8. The digital watermark embedding apparatus according to claim 2, wherein

the target value restorable value is a value obtained by scaling the target value;

and

the setting unit selects a scale power for scaling the target value so as to decrease the influence on the digital content for the target value corresponding to the position.

9. The digital watermark embedding apparatus according to claim 1, wherein

the digital content into which same watermark information is to be embedded is a content dividable into a plurality sub-contents, and a same topological invariant corresponding to the watermark information is set to the plurality of sub-contents.

10. The digital watermark embedding apparatus according to claim 1, wherein

the content into which a same watermark information is to be embedded is a content dividable into a plurality sub-contents, and a value according to a pseudo-random number generated based on the watermark information is set, as the topological invariant, to the plurality of sub-contents.

11. The digital watermark embedding apparatus according to claim 1, wherein

the content is image data of a still image or moving image frames;

and

the part is a pixel value vector of the image data.

12. The digital watermark embedding apparatus according to claim 1, wherein

the content is moving image data;

and

the part is a pixel value vector of the moving image data.

13. The digital watermark embedding apparatus according to claim 1, wherein

the content is voice data;

and

the part is an amplitude value vector of the voice data.

14. The digital watermark embedding apparatus according to claim 1, wherein

the predetermined topological invariant is a homotopy invariant.

16. The digital watermark detecting apparatus according to claim 15, wherein

said detector obtains a representative value representing a divided region obtained by dividing the content in a spatial manner or a time-basis manner based on a value read from a predetermined part of one or a plurality of bit strings corresponding to a spatial or time-basis position of the divided region, and obtains the predetermined topological invariant based on the representative value representing the divided region.

17. The digital watermark detecting apparatus according to claim 16, wherein

a plurality of positions are provided, a content of one divided region is constituted by the bit string corresponding to the plurality of positions, and the representative value is an average value of values of the predetermined part of the plurality of bit strings.

18. The digital watermark detecting apparatus according to claim 16, wherein

said detector obtains a target value standardizing the representative value of the divided region, and performs a predetermined summing arithmetic operation for the target value and a difference in target values, thereby obtaining the predetermined topological invariant.

19. The digital watermark detecting apparatus according to claim 15, wherein

the content into which a same watermark information is to be embedded is a content dividable into a plurality of sub-contents, topological invariants are detected from the plurality of sub-contents, respectively, and the watermark information is obtained based on the obtained topological invariants.

20. The digital watermark detecting apparatus according to claim 15, wherein

the content is image data of a still image or moving image frames;

and

the part is a pixel value vector of the image data.

21. The digital watermark detecting apparatus according to claim 15, wherein

the content is moving image data;

and

the part is a pixel value vector of the moving image data.

22. The digital watermark detecting apparatus according to claim 15, wherein

the content is voice data;

and

the part is an amplitude value vector of the voice data.

23. The digital watermark detecting apparatus according to claim 15, wherein

the predetermined topological invariant is a homotopy invariant.

15. A digital watermark detecting apparatus for detecting watermark information from a digital content, comprising:

a detector configured to detect a predetermined topological invariant set to the digital content based on a content into which the watermark information is embedded; and

an output unit configured to output watermark information corresponding to the detected predetermined topological invariant.

24. A digital watermark embedding method for embedding watermark information into a digital content, comprising:

obtaining a predetermined topological invariant corresponding to the watermark information to be embedded into the digital content; and

setting the predetermined topological invariant to the digital content by modifying said digital content into which said watermark information is to be embedded.

25. A digital watermark detecting method for detecting watermark information from a digital content, comprising:

detecting a predetermined topological invariant set to the digital content based a content into which the watermark information is embedded; and

outputting watermark information corresponding to the detected predetermined topological invariant.

26. An article of manufacture comprising a computer usable medium having computer readable program code means embodied therein, the computer readable program code means comprising:

computer readable program code means for causing a computer to obtain a predetermined topological invariant corresponding to the watermark information to be embedded into the digital content; and

computer readable program code means for causing a computer to set the predetermined topological invariant to the digital content by modifying said digital content into which said watermark information is to be embedded.

27. An article of manufacture comprising a computer usable medium having computer readable program code means embodied therein, the computer readable program code means comprising:

computer readable program code means for causing a computer to detect a predetermined topological invariant set to the digital content based on a content into which the watermark information is embedded; and

computer readable program code means for causing a computer to output watermark information corresponding to the detected predetermined topological invariant.