Methods, apparatus and systems for an electronic watermark having resistance to scaling

• US 20020114490A1
• Filed: 09/11/2001
• Published: 08/22/2002
• Est. Priority Date: 09/12/2000
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Taniguchi, Masaaki, Kamijoh, Kohichi, Shimizu, Shuhichi, Sugihara, Ryoh
• Granted Patent: US 7,006,655 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 2201/0061 Embedding of the watermark in each block of the image, e.g. segmented watermarking
• 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

Abstract

The present invention provides methods, apparatus and systems for embedding and detecting an electronic watermark without requiring signals for geometric compensation. A particular embodiment uses a periodic pattern with repetition as an embedded pattern itself, which has information embedded as an electronic watermark, and observes the change of its period upon detection to calculate the scaling factor. When detecting the electronic watermark, the scaling factor of images is calculated from digital data that underwent the scaling processing, and then the processing to detect the electronic watermark is performed based on the obtained scaling factor.

Claims

1. A method for performing an electronic watermark on digital data, comprising the steps of:

preparing a digital embedded pattern having information that is to be embedded as an electronic watermark in digital data; and

embedding said embedded pattern in said digital data at least twice or more repeatedly;

wherein said embedded pattern has a repetitive pattern in the horizontal and/or vertical direction wherein step of embedding employs a known repetition rate.

4. The method according to claim 1 or claim 3, wherein the step of embedding comprises embedding said embedded pattern with alteration.

14. A method as recited in claim 1, wherein the step of embedding includes employing a known repetition rate.

16. A method as recited in claim 1, wherein the step of embedding is performed without requiring signals for geometric compensation.

2. A method for detecting an electronic watermark embedded in digital data, comprising the steps of:

when detecting an embedded pattern that has been embedded in digital data at least twice or more repeatedly, finding a period having a maximum correlation by autocorrelation of said embedded repetitive pattern;

detecting a scaling factor added to a frame from a change of said period; and

detecting said embedded pattern using said scaling factor employing the repetition rate of the embedded pattern.

15. A method as recited in claim 2, wherein the step of detecting an embedded pattern includes employing a known repetition rate of said embedded pattern.

17. A method as recited in claim 2, wherein the step of detecting is performed without requiring signals for geometric compensation.

3. A method for performing an electronic watermark on digital data composed of plural frames, comprising the steps of:

preparing a digital embedded pattern having information that is to be embedded as an electronic watermark in digital data; and

embedding said embedded pattern in one of said frames at least twice or more repeatedly;

wherein said embedded pattern has a repetitive pattern in the horizontal or vertical direction.

5. A method for detecting an electronic watermark embedded in digital data composed of plural frames, comprising the steps of:

when detecting an embedded pattern that has been embedded in one of said frames at least twice or more repeatedly, finding a period having a maximum correlation by autocorrelation of the pattern in said one frame; and

detecting a scaling factor added to the frame from a change of said period.

6. A method comprising:

performing an electronic watermark on MPEG data composed of plural frames, wherein said MPEG data is divided into intra blocks of 8×

8 pixels in size and further performed DCT, including the steps of;

preparing an embedded pattern having information that is to be embedded as an electronic watermark in said MPEG data, the embedded pattern being composed of a tuple of base block patterns of 8×

4 pixels in size that are orthogonal each other; and

embedding said embedded pattern in one of said frames at least twice or more repeatedly;

wherein said embedded pattern has a repetitive pattern in the horizontal or vertical direction.

7. A method for performing an electronic watermark on compressed digital data, comprising the steps of:

preparing a digital embedded pattern having information that is to be embedded as an electronic watermark in digital data; and

embedding said embedded pattern in said digital data at least twice or more repeatedly;

wherein said embedded pattern has a repetitive pattern in the horizontal or vertical direction, an autocorrelation peak of said repetitive pattern appearing differently when finding a scaling factor upon detection.

8. A method for detecting an electronic watermark embedded in compressed digital data, comprising the steps of:

when detecting an embedded pattern that has been embedded in digital data at least twice or more repeatedly, finding a period having a maximum correlation by autocorrelation of said embedded pattern;

detecting a scaling factor added to the digital data from a change of said period; and

detecting information embedded in the digital data by applying a shift pattern prepared in advance to a detected block.

9. A system for performing an electronic watermark on digital data, comprising:

means for preparing a digital embedded pattern having information that is to be embedded as an electronic watermark in digital data; and

means for embedding said embedded pattern in said digital data at least twice or more repeatedly;

wherein said embedded pattern has a repetitive pattern in the horizontal or vertical direction.

10. The system according to claim 9, wherein the means for embedding comprises embedding said embedded pattern with alteration.

20. A computer program product comprising a computer usable medium having computer readable program code means embodied therein for causing a watermark to be embedded, the computer readable program code means in said computer program product comprising computer readable program code means for causing a computer to effect the functions of claim 9.

11. A system for detecting an electronic watermark embedded in digital data, comprising:

when detecting an embedded pattern that has been embedded in digital data at least twice or more repeatedly, means for finding a period having a maximum correlation by autocorrelation of said embedded repetitive pattern;

means for detecting a scaling factor added to the digital data from a change of said period; and

means for detecting said embedded pattern using said scaling factor.

18. An article of manufacture comprising a computer usable medium having computer readable program code means embodied therein for causing a watermark to be embedded, the computer readable program code means in said article of manufacture comprising computer readable program code means for causing a computer to effect the steps of claim 16.

19. An article of manufacture comprising a computer usable medium having computer readable program code means embodied therein for causing a watermark to be detected, the computer readable program code means in said article of manufacture comprising computer readable program code means for causing a computer to effect the steps of claim 17.

21. A computer program product comprising a computer usable medium having computer readable program code means embodied therein for causing a watermark to be detected, the computer readable program code means in said computer program product comprising computer readable program code means for causing a computer to effect the functions of claim 11.

12. A computer readable storage medium tangibly embodying a program to cause a computer to perform an electronic watermark on digital data, the program comprising:

a function of preparing a digital embedded pattern having information that is to be embedded as an electronic watermark in digital data; and

a function of embedding said embedded pattern in said digital data at least twice or more repeatedly;

wherein said embedded pattern has a repetitive pattern in the horizontal or vertical direction.

13. A computer readable storage medium tangibly embodying a program to cause a computer to detect an electronic watermark embedded in digital data, the program comprising:

when detecting an embedded pattern that has been embedded in digital data at least twice or more repeatedly, a function of finding a period having a maximum correlation by autocorrelation of said embedded repetitive pattern;

a function of detecting a scaling factor added to a frame from a change of said period; and

a function of detecting said embedded pattern using said scaling factor.