• Journal of the Institute of Electronics Engineers of Korea CI
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• v.37 no.6
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• pp.32-40
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• 2000

In this paper, we proposed a wavelet-based digital watermarking algorithm using human visual system and subband-adaptive threshold. After the original image is transformed by discrete wavelet transform, the perceptually significant coefficients of the each subband excluding the lowest level subbands are utilized to embed the watermark. To select perceptually significant coefficients for each subband, we use subband-adaptive threshold. For the selected coefficients in the high frequency subbands, the watermark is embedded using HVS. For those of the baseband, the watermark is embedded by conventional embedding method. We tested the performance of the proposed algorithm compared with conventional watermarking algorithm by computer simulation. The experimental results show that the proposed watermarking algorithm is less visible to human eyes and more robust to image compressions, image processings, and geometric transformations than the conventional algorithm.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.8
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• pp.1589-1596
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• 2017

In synchronous secure communications, a synchronization signal is transmitted over the same channel where ciphertext is transmitted for cryptographic synchronization between an encryptor and a decryptor, so, it causes data rate lowering and transmission delay for plain communication. Especially, in poor environments such as wireless channels and so on, since secure communications require a periodic resynchronization protocol, synchronization signal transmission method can dominate its quality. In this paper, we proposed a new synchronization signal transmission method without additional bandwidth as well as resynchronization protocol based on it. We embeded a synchronization signal as a watermark in a transmission image and restored it from a detected watermark in the decryptor. Experimental results of image have demonstrated that the proposed synchronization signal transmission method using watermarking is efficient in transmission rate and can support reliable synchronization detection.

• Journal of the Institute of Electronics Engineers of Korea TE
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• v.39 no.3
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• pp.21-27
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• 2002

The digital watermarking methods have been proposed as a solution for solving the illegal copying and proof of ownership problems in the context of multimedia data. But it is still difficult to have been overcame the problem of the protection of property to multimedia data, such as digital images, digital video, and digital audio. This paper describes a watermarking algorithm that embeds non-linearly audio logo watermark data which is converted from audio signal of the ownership in the components of pixel intensities in an original image and that insists of ownership by hearing the audio signal transformed from the extracted audio logo through the speaker. Experimental results show that our algorithm using audio logo proposed in this paper is robust against attacks such as particularly lossy JPEG image compression. 

• The Transactions of the Korea Information Processing Society
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• v.7 no.1
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• pp.296-305
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• 2000

In this paper, we propose the method of embedding the encrypted digital watermark in quantization coefficient when we encode the image data in the process of JPEC. The proposed method is as following. After a DCT coefficient of each block is quantized, we arrange the quantization coefficient as on dimension with a zigzag scan and replace each block. By applying even-odd feature of frequency of the encrypted watermark to a quantization coefficient of some fixed domain of replaced each block and embedding it, we obtain the compressed image data by encoding after placing it in the order prior to replacement. The advantages of the proposed method here are as follows: We can embed many information keeping a secret as much as possible by using the algorithm of block replacement. We can control the amount of embedding of each use, as we embed the encrypted information by selecting some fixed domain of a quantization coefficient, we can fix the embedding data regardless of the image and the value of quantization. We verified the results by experiments and analyzed the efficiency of them in comparison with the former study.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.42 no.6
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• pp.149-158
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• 2005

This paper proposed a blind watermarking method for video contents which satisfies both the invisibility and the robustness to attacks to prohibit counterfeiting, modification, illegal usage and illegal re-production of video contents. This watermarking algorithm targets MPEG compression system and was designed to control the amount of watermarking to be inserted according to the adaptive quantization scale code to follow the adaptive quantization of the compression system. The inserting positions of the watermark were chosen by considering the frequency property of an image and horizontal, vertical and diagonal property of a $8{\times}8$ image block. Also the amount of watermarking for each watermark bit was decided by considering the quantization step. This algorithm was implemented by C++ and experimented for invisibility and robustness with MPEG-2 system. The experiment results showed that the method satisfied enough the invisibility of the inserted watermark and robustness against attacks. For the general attacks, the error rate of the extracted watermark was less than $10\%$, which is enough in robustness against the attacks. Therefore, this algorithm is expected to be used effectively as a part in many MPEG systems for real-time watermarking, especially in the sensitive applications to the network environments.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.5 no.1
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• pp.118-124
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• 2001

In this paper, we proposed the novel digital watermarking for color still image using the characteristics of human visual system and the distribution of DCT coefficients. We insert watermark signal in the chromatic components of YCrCb color space according the characteristics of the human visual system that chromatic component are less sensitive than achromatic components. In order to extract the watermark signal, we use the relationship among the DCT coefficients of watermarked image without using original one. Simulation results show that the proposed watermarking method is better quality on invisibility than the conventional methods.

• Proceedings of the Korea Information Processing Society Conference
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• 2003.05c
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• pp.2189-2192
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• 2003

전자정부, 전자상거래의 활성화로 디지털 문서가 빠른 속도로 유통되고 있기에 이에 대한 효과적인 보호대책이 필요한 실정이다. 본 논문에서는 Window Pattern을 이용하여 Binary Image에 저작권 정보를 삽입하는 방안을 제안한다. 삽입대상 Window Pattern을 결정하고 이러한 Pattern으로 원본 영상을 Scan하면서 픽셀 값에 변화를 주게 된다. 이렇게 되어 하나의 Pattern에 1bit의 정보의 삽입이 가능하게 되고 추출 시 원본을 필요로 하지 않으며 실용성이 높고 적용분야도 넓다.

• Journal of Digital Contents Society
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• v.5 no.4
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• pp.316-320
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• 2004

In this paper, we propose OFDM/QPSK technique for copyright protection of image data to insert watermark. And, we improve performance of restoration watermark by Reed-Solomon coding that robust burst error. In here, we consider several factors about external effect of image over OFDM/QPSK transmission system.

• The KIPS Transactions:PartB
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• v.8B no.5
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• pp.579-586
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• 2001

Digital watermarking is to embed imperceptible mark into image, video, audio, and text data to prevent the illegal copy of multimedia data. arbitrary modification, and also illegal sales of the copies without agreement of copyright ownership. In this paper, we study for the embedding and extraction of watermark key using wavelet in the luminance signal in order to implement the system to protect the copyright for image MPEG. First, the original image is analyzed into frequency domain by discrete wavelet transform. The RSA(Rivest, Shamir, Aldeman) public key of the coded target is RUN parameter of VLD(variable length coding). Because the high relationship among the adjacent RUN parameters effect the whole image, it prevents non-authorizer not to possess private key from behaving illegally. The Results show that the proposed method provides better moving picture and the distortion more key of insert than direct coded method on low-frequency domain based DCT.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.1C
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• pp.105-112
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• 2009

In this paper, we propose a digital watermarking method using Multi-resolution Characteristic of 2D CAT (2D cellular automata transform). Firstly, we select the gateway values to generate a basis function and the basis function transforms images into cellular automata space. Then, we embed the random bit sequence as watermark in specific parts of cellular automata transform coefficients. The proposed method not only verifies higher fidelity than the existing method but also stronger stability on JPEG lossy compression, filtering, sharpening and noise through tests for robustness. Moreover, the proposed scheme allows only one 2D CAT basis function per gateway value. Since there are $2^{96}$ possible gateway values.