• Proceedings of the IEEK Conference
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• 2002.07b
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• pp.868-871
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• 2002

Nowadays, zerotrees based digital watermarking techniques are considered to be an efficient watermarking technique used for multimedia data in a compressed form. This paper presents a technique for watermarking an image, by employing zerotrees derived from the wavelet packet coefficients of the transformed image to carry the watermark signal. By setting a proper threshold in zerotrees determining process, the watermark signal can be recovered without the need of original image. With our proposed technique, more amount of watermark signal can be embedded within the image, compared to ordinary wavelet transform based techniques. The experimental results show the improved performance in both qualities of the resultant watermarked image and robustness of the embedded watermark signal against common signal processing such as brightness/contrast enhancement, high-pass filtering, Gaussian noise adding and JPEG compression scheme

• Journal of Korea Multimedia Society
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• v.9 no.10
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• pp.1276-1281
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• 2006

In this paper, We proposed a robust blind digital watermarking algorithm using variance and DCT domain. The proposed method embedded watermark signals into DC components of $8{\times}8$ block DCT using valiance, texture regions and smooth regions. In the digital watermarking algorithms using DCT domain, more robustness can be achieved if watermarks are embedded in DC components since DC components have much larger perceptual capacity than AC components. Experiment showed that robustness of the proposed method better than that of the conventional methods in JPEG quality and scaling attack.

• Journal of Digital Contents Society
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• v.6 no.2
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• pp.119-123
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• 2005

We proposed a method of effective watermarking based m HVS. To speak generally, HVS parameters are contrast sensitivity, texture degree, entropy sensitivity and standard of deviation, etc. The aim of this paper is evaluated by the experiments of imperceptibility and correctness of watermark. According to some experimental results, contrast sensitivity function is superior in smooth image. On the other hand, standard of deviation provides good results in rough images. Consequently, how to select the parameters considering image attribute is key problem in effective watermarking.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.2
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• pp.233-242
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• 2009

This paper intend to show the affect of the intra-prediction on the typical digital watermarking method and the fact that the watermarking method has very low effectiveness when it is performed for the intra-frames of H.264. The target watermarking method was the one for imperceptibility and robustness and was assumed to be performed during the intra-compression process by the H.264 technique. Also this method was assumed to insert watermark data and to extract it for certification if needed. The problem is that the resulting data from the re-engineering of the watermark insertion process to extract the watermark data is different from the one before. We experimentally showed that it stems from the intra-prediction itself. That is, we showed that the resulting image data from only compression without watermarking changes if it is re-compressed by the same conditions as the first compression and it is because the intra-prediction modes as well as the coefficient values change. Also, we applied one blind and one semi-blind watermarking methods to show that the typical attacks after watermarking makes this problem much more serious and lowers the effectiveness of the watermarking method dramatically. Therefore we concluded by considering the experimental data that a typical watermarking method which has been researched so far cannot guarantee the effectiveness of intra-frame watermarking and it is highly required to developed a new kind of methodologies.

• Proceedings of the IEEK Conference
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• 2000.09a
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• pp.701-704
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• 2000

In this paper, we focus on digital watermarking for color images. At first, in order to embed the watermark signal in color image, we converted RGB color space to YCbCr color space which is a world-wide digital component video standard. In addition, we adopted the acceptable degree of color difference in order to keep the invisibility.

• Journal of the Institute of Convergence Signal Processing
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• v.14 no.1
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• pp.13-20
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• 2013

A combined DWT and DCT based watermarking technique of low frequency watermarking with weighted correction is proposed. The DWT has excellent spatial localization, frequency spread and multi-resolution characteristics, which are similar to the theoretical models of the human visual system (HVS). The DCT based watermarking techniques offer compression while DWT based watermarking techniques offer scalability. These desirable properties are used in this combined watermarking technique. In the proposed method watermark bits are embedded in the low frequency band of each DCT block of selected DWT sub-band. The weighted correction is also used to improve the imperceptibility. The extracting procedure reverses the embedding operations without the reference of the original image. Compared with the similar approach by DCT based approach and DWT based approach, the experimental results show that the proposed algorithm apparently preserves superiori mage quality and robustness under various attacks such as JPEG compression, cropping, sharping, contrast adjustments and so on.

• 한국ITS학회:학술대회논문집
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• 2010.05a
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• pp.1-4
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• 2010

• Journal of information and communication convergence engineering
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• v.9 no.6
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• pp.689-694
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• 2011

Cellular automata are discrete dynamical systems, which provide the basis for the synthesis of complex emergent behavior. This paper proposes a new algorithm of digital watermarking based on cellular automata transform (CAT). The idea of two-dimensional CAT is introduced into the algorithm. After the original image is disassembled with 2D CAT, the watermark information is embedded into the Middle-frequency of the carrier picture. Cellular automata have a huge number of combinations, such as gateway values, rule numbers, initial configuration, boundary condition, etc. Using CAT, the robustness of the watermark will be tremendous strengthened as well as its imperceptibility. Experimental results show that this algorithm can resist some usual attacks such as compression, sharpening and so on. The proposed method is robust to different attacks and is more security.

• Proceedings of the IEEK Conference
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• 2002.07a
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• pp.478-481
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• 2002

In this paper, the zerotrees of DWT is proposed to be used in a speech based digital watermarking for digital images. Since in this research work the raw speech and its content are used as a watermark signal, in the watermarking scheme, the PCM coded speech signal is embedded into a sequence of images. The performance of the scheme is evaluated by the PSNR obtained from the watermarked images and the strength of attacks the embedded speech signal can survive. Moreover, since in this research work the contents contained in the speech is used to identify the specific information hidden in the embedded signal. The speech signal after being extracted from the watermarked images is played back to the listeners to determine whether its content is intelligible or not. The experimental results show impressive performance of the scheme implementing our proposed technique, judged by the higher robustness obtained form the embedded signal against various types of attack, including brightness/contrast enhancement, Twirling, highpass filtering and JPEG compression standard.

• Proceedings of the IEEK Conference
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• 2003.11b
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• pp.247-250
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• 2003

This paper proposed to digital watermarking technique for architectural drawing using LINES and ARCs based on vertex in CAD system to prevent infringement of copyright from unlawfulness reproductions and distribution. After extract LINES and ARCs from designed drawing, we embed watermarks using adaptive algorithm in each characteristics. Watermarks robust to various attacks like as geometrical transformation as being embedded in LINE's length and ARC's angle information. Also, the proposed method satisfies enough transparency about watermarked drawing because have suitable embedding strength to each component. By experimental result, we confirmed robustness and invisibility of embedded watermarks in several conversions of architectural design drawing.