2002 Fiscal Year Final Research Report Summary
A study on digital watermark technique based on the phase modulation of sampling lattice and application to still picture
| Project/Area Number |
12650405
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
情報通信工学
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| Research Institution | Hiroshima Kokusai Gakuin University |
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Principal Investigator |
MINAMI Noriaki Hiroshima Kokusai Gakuin University, Graduate of Engineering/Faculty of Contemporary Sociology, Associate Professor, 大学院・工学研究科・現代社会学部, 助教授 (60320024)
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| Project Period (FY) |
2000 – 2002
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| Keywords | picture / data embedding / phase modulation / sampling lattice / digital watermark |
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| Research Abstract |
1. The improvement on the attack resistance
On this method, an original picture is necessary for decoding embedding data as a standard reference information. We positively utilize this feature and propose a new method in which we use a processed picture by data compression coding instead of the original pictures as the standard reference information. We examine the proposed method with the authorized source coding (that is, JPEG). The results show that the new method can exactly improve error rate characteristic such that, for instance, as "Zelda", approximately 1, 000 embedded data bits are decoded correctly with the JPEG compression ration of 17 under the degradation of the signal-to-noise ratio within approximately 01. dB.
2. A note on the encoding and decoding signal processing
From the viewpoint of decoding error performance, we have discussed the encoding signal processing for the phase modulation based data embedding method by comparing the robustness against the degradation due to the JPEG data compression. As a result, we conclude that the band-limited interpolation and cubic spline interpolation give better performance, compared with the bi-linear interpolation.
3. The disclosing betrayers in collusion attack
The effect of the simplest collusion attack with this method, based on the use of the arithmetic mean of pixel values by betrayers is examined. The results show that by embedding the Walsh function, the new method can successfully disclose who they are.
4. Digital watermark based on error correcting codes and cryptography
We propose a new technique which can detect the forgery of the digital image data by applying both coding theory and cryptology. We show that it is important to combine error correcting code with cryptogram in an appropriate way. We also present an example of new techniques that use RSA cryptogram.
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