• Proceedings of the IEEK Conference
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• 2001.09a
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• pp.223-226
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• 2001

In this paper, we propose a robust and fragile watermarking technique for tamper proofing of still images. Robust watermarks are embedded by quantization with a robust quantization step-size, and it is imperceptible value for human visual system. Fragile watermarks are embedded by thresholding and quantization with EW(Embedded Zerotree Wavelet) algorithm. The proposed method enables us to distinguish malicious change from non-malicious change. Futhermore this technique enables us to find tampering regions and degrees.

• Proceedings of the IEEK Conference
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• 2000.09a
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• pp.519-522
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• 2000

Digital watermarking has been proposed as a solution to the problem of copyright protection of the multimedia documents. In this paper a new watermarking method for digital images operating in the frequency domain is proposed. In our approach, DCT coefficients of the watermark are added to the low frequency region of the host image, and extract it using the Wiener Filter. Due to the characteristic of the wiener filtering, the watermark is robust to various image processing techniques. Experimental results show that it is possible to reliably extract the watermark without degrading image quality.

• 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.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 2006.07a
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• pp.452-452
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• 2006

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 2004.07a
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• pp.232-232
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• 2004

• Proceedings of the IEEK Conference
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• 2003.11a
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• pp.213-216
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• 2003

In this paper, we propose a digital watermarking method using the spread spectrum techniques in DCT domain. Watermark is embedded in the middle band frequencies of 8$\times$8 DCT block. Therefore, we improve image quality and robustness. Experiment results show that the proposed watermark is robust against various attack.

• Proceedings of the IEEK Conference
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• 2003.07e
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• pp.1791-1794
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• 2003

In this Paper, we propose a new watermarking algorithm for 1-bit image authentication using block operation. Observing 3${\times}$3 block patterns, we find the regions to watermark, We describe a specific scheme how to generate data to embed and find pixels most probably invisible under modifications. We also show the experimental results of proposed algorithm.

• Proceedings of the IEEK Conference
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• 2002.06d
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• pp.359-362
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• 2002

In this paper, we propose a new feature-based text watermarking for the binary text image. The structure of specific characters from preprocessed text image are modified to embed watermark. Watermark message are embedded and detected by the following method; Hole line disconnect using the connectivity of the character containing a hole, Center line shift using the hole area and Differential encoding using difference of flippable score points. Experimental results show that the proposed method is robust to rotation and scaling distortion.

• Proceedings of the IEEK Conference
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• 2002.06d
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• pp.105-108
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• 2002

This paper proposes a new watermarking algorithm to embed data in 1-bit images using edges for protecting illegal copies or modifications. This method is based on edge detection to decide the most invisible region. This paper also introduces a new shuffling method which embeds data in each blocks uniformly and finds Positions under the limited attacks. In experiment, we compare the proposed shuffling method with M. Wu's method.

• The Magazine of Kiice
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• v.5 no.1
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• pp.38-48
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• 2004

정보기술(Information Technology ; IT)의 발전을 대표하는 상징 중에 하나는 것은 각 가정에 설치된 개인용 컴퓨터(Personal Computer)를 들 수 있다. 즉, PC의 보급이 광범위해지면서 PC가 생산, 보유한 정보를 서로 공유하고 교환할 필요성을 느끼게 되어 특정 개인의 PC에만 국한되지 않고 networked PC가 필요하게 되었고, PC간의 데이터통신을 위한 다양한 기술들이 개발되기 시작하였다. 그 첫 번째 시도가 지리적으로 가까이 있는 컴퓨터간의 통신네트워크를 구성하려는 시도였는데, 이것이 근거리 통신망(LAN)과 1990년대 중반에 탄생한 웹(WWW; world wide web)의 출현이다. (중략)