Traditional watermarking methods based on spectrum manipulation use watermark bit as a colored noise. However, those methods show poor robustness for filtering and audio compression because of only a few spectrum coefficients being modified. In this paper, we propose a new algorithm for robust audio watermarking by using spectrum warping. Our watermark-embedding scheme is not based on spectrum coefficient manipulation, but based on warping spectrum that shifts a block of spectrum coefficients nonlinearly. The host audio signal is divided appropriately into small segments and then a non-orthogonal transform, such as bi-linear transform, is used for each segment to embed as well as to extract watermarks. Because the proposed scheme uses small segment length, we can afford to embed signature information many times into audio signal without severe degradation of SNR. Our multiple embedding scheme increases robustness against abnormal distortion of watermarked signal and has no bit error rate in MPEG1 Layer-3 128 kbps and 96 kbps compression as well as low/high pass filtering.

Compared with much research in the spatial-domain and transform-domain watermarking techniques, VQ-based watermarking technique has not been fully treated. A digital image watermarking scheme based on vector quantisation (VQ) is proposed to improve the degree of spreading watermark information. By partitioning the codebook into 3 groups, the scheme tries to embed one binary information for each block. The scheme spreads the watermark information almost evenly over the image with little extra distortion. The experimental results prove the efficiency and effectiveness of the scheme.

A new method of error concealment for MPEG videos, in which motion vectors are hidden in an MPEG bitstream as a watermark, is proposed in this paper. Several conventional methods conceal error regions by using motion vectors, which are re-estimated in a decoding process. These methods, however, have two problems: (1) The accuracy of a re-estimated motion vector is lower than that of an estimated motion vector in an encoding process. (2) A large amount of calculation is required to re-estimate motion vectors. The proposed method overcomes these problems by using hidden accurate motion vectors. That is, it hides several bits in each 88 DCT block of all frames and, simultaneously, inhibits the image degradation caused by hiding motion vectors. In addition, it has upward compatibility with a standard MPEG decoder and can be combined with conventional methods. Simulation results show that the accuracy of error concealment by the new method is higher than that of the conventional methods.

In this paper, we discuss digital watermarking techniques besed on modifying the spectral coefficient of an image, classified into quantization-based and correlation-based watermarking techniques. We first present a model of the watermark embedding and extracting processes and examine the robustness of the watermarking system against common image processing. Based on the result, we clarify the reason why detection errors occur in the watermark extracting process and give a method for evaluating the performance of the watermarking system. And then we study an improvement of the watermark extracting process using the deconvolution technique and present some concluding remarks in the last section.

This paper focuses on the watermarking system using a controlled quantization process. We first present a model of the watermark embedding and extracting processes and carry out their analyses. Then we examine the robustness of the watermarking system against common image processing and clarify the reason why detection errors occur in the watermark extracting process. Based on the result, we improve the watermark extracting process and design robust watermarking systems. The improvement is accomplished using a deconvolution filter and neural network techniques. Numerical experiments using the DCT-based watermarking system show good performance as expected by us.

In this paper, a novel adaptive digital watermarking approach based upon human visual system model and fuzzy clustering technique is proposed. The human visual system model is utilized to guarantee that the watermarked image is imperceptible. The fuzzy clustering approach has been employed to obtain the different strength of watermark by the local characters of image. In our experiments, this scheme allows us to provide a more robust and transparent watermark.

This paper proposes a new heuristic algorithm FMDB for the minimum initial marking problem MIM of Petri nets: "Given a Petri net and a firing count vector X, find an initial marking M0, with the minimum total token number, for which there is a sequence δ of transitions such that each transition t appears exactly X(t) times in δ, the first transition is firable on M0 and the rest can be fired one by one subsequently. " Experimental results show that FMDB produces better solutions than any known algorithm.

Watermarking techniques proposed up to now have some measure of robustness against non-geometrical alteration, however, most of them are not so robust against geometrical alteration. As also for video watermarking, small translation, scaling, rotation, affine transformation can be effective attacks on the watermark. In this paper, we propose an image correction scheme for video watermarking extraction. This scheme embeds 'patchwork' into digital video data for detection of positions, and corrects the images attacked by geometrical alteration on the basis of the detected positions. We also show the simulation results of applying proposed scheme to the conventional watermarking technique.

In this paper, we define content-identifier (ContentID) to represent the characteristics of shot. The ContentID carries both positional and temporal color information. Based on the concept of ContentID, we propose a video retrieval method. The method is robust to compression, format conversion, frame dropping and noise such as watermark and so on. Furthermore, based on our retrieval method, we implemented a copyright protection system for digital video using spread-spectrum based watermarking technique.

A repeating watermarking technique based on visual secret sharing (VSS) scheme provides the watermark repeated throughout the image for avoiding the image cropping. In this paper, the watermark is divided into public watermark and secret watermark by using the VSS scheme to improve the security of the proposed watermarking technique. Unlike the traditional methods, the original watermark does not have to be embedded into the host image directly and, thus, it is hard to be detected or removed by the pirates or hackers. The retrieved watermark extracted from the watermarked image does not require the complete original image, but requires a secret watermark. Furthermore, the watermarking technique suits the watermark with an adaptive size of binary image for designing the watermarking system. The experimental results show that the proposed method can withstand the common image processing operations, such as filtering, lossy compression and the cropping attacking etc. The embedded watermark is imperceptible, and that the extracted watermark identifies clearly the owner's copyright.

A new digital watermark approach based on fractal image coding is proposed in this letter. We present a way to use the fractal code as a means of embedding a watermark. The proposed approach has shown to be resistant to the JPEG lossy compression. Moreover, the digital watermark can be simply extracted from the watermarked image without resorting to the original image.

A quantization-based watermarking system for motion pictures is proposed. In particular, methods for improving the image quality of watermarked video, the watermarking data tolerance, and the accuracy of watermark data detection are described. A quantitative evaluation of the reliability of watermarked data, which has not generally been discussed up to now, is also performed.

In many applications of digital video database systems such as digital library, video data is often compressed with MPEG video algorithms. It will be an important technique to insert the additional information data like indexes and contents effectively into video database which is compressed with MPEG, because we can always deal with the additional information with video data itself easily. We propose a method for inserting optional binary data such as index information of digital library into MPEG-1 and -2 bitstreams. The binary data inserted MPEG video bitstreams using our proposed scheme are also according to the specification of the MPEG video frame structure. The proposed method allows us to extract the inserted binary data perfectly though MPEG-1 and -2 video are lossy algorithms. And the quality of decoded images after extracting added information is almost the same as that of ordinary MPEG bitstreams. Furthermore, traditional standard MPEG-1 and -2 video decoder which can not extract inserted binary data can also decode images from the binary data inserted MPEG video bitstreams without obvious image degradation. There are some different points between the proposed insertion technique of the binary data and the watermarking technique. The technique of watermarking prepares to deal with alter watermarking by others. And the technique of watermarking is required for the identification of the signature and the perfect extraction of the inserted image signature is not required in the lossy MPEG video environment. On the other hand, we have to extract all of the inserted binary information data correctly with the insertion technique of the binary information. Simulations using MPEG video sequences with inserted binary data are presented to quantify some performance factors concerned. We have not heard about inserting data method which purpose is such as index and content information insertion.

This letter proposes improvement to the previously presented watermarking method which spreads an ID pattern with a random sequence and embeds it throughout the spatial domain of an image. The proposed method can extract embedded watermarks without an original image even from images converted by brightness/contrast conversion, edge-enhancement, posterization and JPEG compression.

It is urgently required to protect copyrights of digital contents since the digital contents can be easily copied without degradation of quality. In this paper, we propose a new watermarking method which spreads an ID pattern with a random sequence and embeds it throughout the spatial domain of a color image. The random sequence is a key for extracting the ID pattern. As an ID pattern is spread throughout an image, we can extract the ID pattern from a part of the image, that is clipped image. We can also confirm authenticity by extracting the same ID pattern from several parts of an image. The proposed method is robust to disturbance by noise addition and image conversion such as brightness-contrast conversion and JPEG compression.

Our basic idea of generating random benchmark circuits, i.e., not generating them directly but applying random transformations to initial circuits was presented at DAC'94. In this paper we make the two major improvements towards the goal of random benchmarking: i.e., increasing the generality, the naturality, the security of random circuits: One is controlling fan-ins of logic gates in the random circuits, and the other is producing the initial circuit also at random but under some control of its on-set size and complexity. Experimental data claiming merits of those improvements are also given.

Many typical control problems such as deadlock avoidance problems and mutual exclusion problems can be formulated as forbidden marking problems. This paper studies a forbidden marking problem in controlled complementary-places Petri nets, which are suitable model for sequential control systems. We show a necessary and sufficient condition for the existence of a control law for this problem. We also obtain a maximally permissive control law which allows a maximal number of transitions to fire subject to a condition that forbidden markings will never be reached.

This paper describes a modeling of the cryptography based on a concept of Petri nets. Movement of tokens in the net model shows a dynamic behavior of systems. On the other hand, the cryptography is considered as a bit operation, so that we can point out a common property between the net structure and the cryptography, which provides our idea that movement of tokens of the net model corresponds to a bitoperation of the cryptography. Some effective keys in the net model are considered by means of the net elements, which are based on T-invariant and net structures. It is shown that the keys of the net structured cryptography provide reasonable strength comparing with the data encryption standard (DES).