Digital watermark embedding method, digital watermark extracting method, recording medium, image recording device, and image replaying device

• US 6,898,297 B2
• Filed: 06/20/2001
• Issued: 05/24/2005
• Est. Priority Date: 06/20/2000
• Status: Expired due to Fees

• Current Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Sugishita, Koji, Inoue, Hisashi, Katsura, Takashi
• Primary Examiner(s): Couso, Jose L.
• Assistant Examiner(s): Lu, Tom Y.
• Application Number:
  US09/885,730
• Publication Number:
  US 20010053238A1
• Time in Patent Office: 1,434 Days
• Field of Search: 382/100, 370/522, 714/100, 714/6, 714/746, 714/776, 714/798, 714/799, 714/800
• US Class Current: 382/100
• CPC Class Codes: G06T 1/005 Robust watermarking, e.g. average attack or collusion attack resistant
• CPC Class Codes: G11B 20/00086 Circuits for prevention of unauthorised reproduction or copying, e.g. piracy indicating unauthorised use of record carriers in general G11B23/28; scrambling for television signal recording H04N5/913; network architectures or network protocols for network security H04L63/00; cryptographic mechanisms or cryptographic arrangements for secret or secure communication H04L9/00
• CPC Class Codes: G11B 20/00884 involving a watermark, i.e. a barely perceptible transformation of the original data which can nevertheless be recognised by an algorithm

Abstract

Embedding data to be embedded as a digital watermark is acquired. Packing data is formed in which the embedding data is repeatedly connected three times or more sequentially without interval. Real embedding information is formed such that a redundancy bit with a fixed length that is used for an error correction of an information bit is added immediately after the information bit in which the packing data is subdivided into data each having a fixed length. The real embedding information is embedded into the image data itself. The embedding mechanism for the information is not easily understood, and security level is high.

Claims

1. A digital watermark embedding method comprising the steps of:

acquiring embedding data to be embedded as a digital watermark;

forming packing data in which said embedding data is repeatedly connected at least three times to be sequential without interval;

forming real embedding information in which redundancy bits with a fixed length that are used for error correction of information bits are added immediately after said information bits in which said packing data is subdivided into data each having a fixed length; and

embedding real embedding information into image data.

2. The digital watermark embedding method of claim 1, further comprising the step of encrypting said embedding data.

3. The digital watermark embedding method of claim 1, further comprising the steps of:

interleaving said real embedding information; and

thereafter multiplexedly embedding said real embedding information.

4. A digital watermark extracting method for extracting a digital watermark from image data into which said digital watermark is embedded according to the digital watermark embedding method as set forth in claim 1, the digital watermark extracting method comprising the steps of:

extracting real embedding information from said image data;

cutting real embedding information into code terms having a fixed length;

making an error correction of information bits located at a front of redundancy bits using redundancy bits located at an end of the code term length, and thereby obtaining information bits that have undergone error correction;

executing a majority decision for each corresponding bit of the obtained information bits, and making an error correction by majority decision; and

treating said information bits that have undergone said error correction by said majority decision as data embedded in an image.

5. A recording medium for recording image data, said recording medium including a data structure stored thereon, said image data being formed from embedding data into an original image data as a digital watermark, said data structure comprising:

an area for storing subdivided data, said subdivided data being formed from subdividing packing data into data each having a fixed length, the packing data being formed from repeatedly connecting said embedding data at least three times sequentially without interval; and

an area for storing redundancy bits with a fixed length that are used for error correction of information bits;

wherein said area for storing said redundancy bits is arranged immediately after said area for storing said subdivided data.

6. The recording medium of claim 5, wherein said embedding data is encrypted.

7. The recording medium of claim 5, wherein said embedding data is interleaved.

8. An image recording device comprising:

embedding data input means for acquiring embedding data to be embedded as a digital watermark;

packing data forming means for forming packing data in which said embedding data is repeatedly connected at least three times sequentially without interval;

redundancy bit addition means for subdividing said packing data into subdivided data, each having a fixed length, and thereafter adding redundancy bits with a fixed length that are used for error correction of information bits immediately after said subdivided data each having the fixed length to output real embedding information;

embedding means for embedding said real embedding information into image data; and

output means for writing information onto a recording medium on the basis of said image data in which said real embedding information is embedded.

9. The image recording device of claim 8, further comprising means for encrypting said embedding data.

10. The recording medium of claim 8, further comprising means for interleaving said real embedding information, and thereafter multiplexedly embedding said real embedding information.

11. The image recording device of claim 8, further comprising image data input means for outputting said image data.

12. The image recording device of claim 11, wherein said image data input means includes image pickup means.

13. An image replaying device comprising image signal output means for outputting an image signal on the basis of information read from a recording medium that records an image concerned in which a digital watermark is embedded as real embedding information, comprising:

means for acquiring said real embedding information containing embedding data to be embedded as a digital watermark;

means for repeatedly connecting packing data in which said embedding data is repeatedly connected at least three times sequentially without interval; and

means for subdividing said packing data into subdivided data, each having a fixed length, and thereafter adding redundancy with a fixed length that are used for error correction of information bits immediately after said subdivided data each having the fixed length to output real embedding information.

14. The image replaying device of claim 13, further comprising means for encrypting said embedding data.

15. The image replaying device of claim 13, further comprising means for interleaving said real embedding information, and thereafter for multiplexedly embedding said real embedding information.

16. The image replaying device of claim 13, further comprising a display device for making a display on the basis of an image signal output by said image signal output means.

17. The image replaying device of claim 13, further comprising:

real embedding information detection means for extracting real embedding information embedded in information read from said recording medium on the basis of said information;

error correction means for making an error correction by said redundancy bits with respect to said real embedding information; and

majority decision means for executing a majority decision for each corresponding bit of said information bits with respect to said real embedding information that has been corrected by said error correction means, and making an error correction by said majority decision.

18. The image replaying device of claim 17, further comprising:

error rate calculation means for calculating an error rate of image data concerned with reference to an error rate in said error correction by said redundancy bits and an error rate in said error correction by majority decision; and

falsification judgment means for comparing an error rate of image data concerned calculated by said error rate calculation means with a predetermined threshold, and, if the error rate of image data concerned exceeds said threshold, judging that a falsification exists, and, if not, judging that no falsification exists.