Yoshiyasu Takahashi

Information Embedding Method for Home Printing of Certifications

In this paper, we describe our dot-pattern code, which can embed information onto the paper. Its main features are 1) no need to reserve a special room for the code, 2) obscure and unnoticeable, 3) comparatively large information capacity, 4) the absolute coordinates in the paper is measurable. We describe how to embed and detect the information onto / from the paper, and we estimate it by examination. From the examination, we found that our dot-pattern code is applicable to various kinds of papers, printers including ink-jet and scanners. We also found that even when the density of the black dot is greater than 6 %, over 8,000 bits could be safely embedded with error rate less than 10-6 . We also found that the embedded information could be detected correctly after the paper had been damaged.

Evaluation of PC-Based Real-Time Watermark Embedding System for Standard-Definition Video Stream

The effectiveness of a previously proposed system for embedding watermarks into video frames in real time using software on an ordinary personal computer was evaluated. The proposed system uses standard-definition(SD) video I/O and is separate from the encoding process, so it can be incorporated into various types of encoding and distribution systems, which makes it well suited for distributing live content. The evaluation results with regard to watermark visibility and survivability, resource consumption, and feasibility show that this system is applicable to various practical uses.

Maintaining image quality when watermarking grayscale comic images for electronic books

Digital watermarking of comic images effectively protects the copyright of the content in electronic book applications. The characteristics of comic images were analyzed to determine the effect of digital watermarking on the line shapes. Modification of the shape edges by conventional watermarking methods can degrade image quality because the human eye is sensitive to the edges. The analysis revealed that slight changes in the black pixels in a comic image are barely perceived by the human eye when the image is displayed on a tablet PC. A method was then developed for embedding watermarks that minimizes modification of the white pixels compared to modification of the black ones. Experimental evaluation showed that this method improves the quality of watermarked grayscale comic images. Watermark robustness was almost the same as that with the conventional method in an assumed use case.

Use of emergable watermarks as copy indicators for securing video content

We propose using emergable watermarks as copy indicators that become visible in video content that has been copied under designated conditions. A watermark pattern is designed that is sensitive to image processing specific to illegal copying. This is done on the basis of the aliasing effect, which causes image distortion when the re-sampling frequency is low. Watermarks using such patterns are embedded in the original video. They become visible only if the copy had been illegally generated by re-encoding with designated scaling. They show, for example, copy indicators, warning the viewer that the video had been illegally copied, and distort the image quality. Testing of a prototype implementation demonstrated the effectiveness of this method. The peak-signal-to-noise-ratio in watermarked video was adjustable by more than 28 dB. Use of this method should help deter the illegal copying and/or distributing of copyrighted videos.

Symbiotic Autonomous Decentralized System on Cooperative Distributed Scheduling

Currently, System of Systems approach becomes more and more important in the field of social infrastructure to adapt various user needs flexibly and efficiently. Symbiotic autonomous decentralized systems is one of System of Systems. In this system, optimizations of both entire system and each system are expected to be achieved simultaneously. However, the symbiotic operation based on free will of each system doesnt go well, because each system has its own key performance indicator and tries to pursue the indicator. In order to promote symbiosis in the systems, we developed Cooperative Distributed Scheduling. As a result of verification with a simulator, we confirmed the total key performance indicator of each system improved by about 17%.

Experiment on video watermark detection system using degraded original images

Watermarks often have to be detected from videos that have experienced such severe image processing as combinations of re-encoding and resizing in real applications. To improve watermark detection performance, this paper proposes a new method consisting of the following four steps: (a) estimate the image processing the watermarked images experienced, (b) apply the estimated image processing to the original images, (c) subtract the degraded original images from the watermarked images, and (d) detect watermarks from the difference images. Under the redistributing threat model, experimental evaluations show that the proposed method yields a detection ratio 34.4-percentage points higher than that yielded by the conventional method M1, which does not use original images.

Evaluation of Audio Watermark System Using Short Detection Time Frame

Assumed applications of copyright protection for music and synthesized voice are discussed. We developed a prototype audio watermark system combining the results of previous studies based on the patchwork algorithm, modifying the amplitude in the time-domain of voiced audio data, and using a reference signal. The results of experimental evaluation show that this our system can detect watermarks in a time frame as short as 2 s.

Integrity verification method for video content using robust watermarking

A method is described for verifying video content integrity by checking the continuity of timecodes embedded as digital watermarks. Conventional verification methods using digital signatures and fragile watermarking are unable to distinguish between attacks and regular modifications and thus are unable to protect against threats to content. The proposed verification method distinguishes attacks against video content from regular modifications by detecting timecodes embedded in consecutive frames of the content and then checking their continuity. A prototype implementation showed that the method is more effective than conventional ones and that it can be used by a variety of applications using video content.

The Estimation of the New Feature Extracting Method for Tamper Detection in Printed Documents

In this paper, we report the experimental result of the estimation of our proposed technique to extract the feature of the printed documents for tamper detection. We have compared the proposed technique which uses median points as a feature and the existing technique which uses the area of the black dots as a feature. As an experiment, we calculated the median point of alphabets and numbers, and printed and scanned to see the probability of the collision, the uniformity of the distribution, invariability during D/A and A/D transform, and the invariability during the ordinal change of paper of our feature extracting method. For the probability of the collision, the proposed method showed lower probability of the collision than the existing one. For the uniformity of the distribution, the proposed method showed a half skew of the existing one. For the invariability during D/A and A/D transform, the proposed method showed the invariability of about a thirtieth of the one of the existing one. For the invariability during the ordinal change of paper, the proposed method showed an eighteenth invariability of the existing one. From the above results, we have concluded that as a feature extracting method, our proposed method is better than the existing one.

Evaluation of Integrity Verification System for Video Content Using Digital Watermarking

The effectiveness of a previously proposed system for verifying video content integrity was investigated using a prototype system. Unlike conventional verification systems using digital signatures and fragile watermarking, the proposed verification system embeds timecodes in consecutive frames of the content, extracts them some time later, and checks their continuity to distinguish attacks from regular modifications. Testing demonstrated that the system maintained picture quality, that the watermarks were robust against regular modifications, and that attacks could be detected reliably and be distinguished from regular modifications. This integrity verification system is thus well suited for a variety of applications using video content.