Ki-Ryong Kwon
Pusan National University
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Publication
Featured researches published by Ki-Ryong Kwon.
Digital Signal Processing | 2007
Suk-Hwan Lee; Ki-Ryong Kwon
This paper proposes 3D mesh watermarking using the CEGI distribution that is robust against mesh simplification, cropping, vertex randomization, and rotation and does not require the original model for realignment or extracting the watermark. In the proposed algorithm, a 3D mesh model is divided into patches using a distance measure, then the watermark bits are embedded into the normal vector direction of the meshes that are mapped into cells with large complex weights in the patch CEGIs. The watermark can be extracted based on two watermark keys, the known center point of each patch and a rank table of the cells in each patch. In a rotated model, the realignment process is accomplished using the above watermark key instead of the original model before extracting the watermark. Experimental results verified the robustness of the proposed algorithm based on watermark extraction after various types of attack.
computational intelligence and security | 2005
Young-Ran Park; Hyunho Kang; Sang-Uk Shin; Ki-Ryong Kwon
This paper presents a steganographic algorithm in digital images to embed a hidden message into cover images. This method is able to provide a high quality stego image in spite of the high capacity of the concealed information. In our method, the number of insertion bits into each pixel is different according to each pixel’s characteristics. That is, the number of insertion bit is dependent on whether the pixel is an edge area or smooth area. We experimented on various images to demonstrate the effectiveness of the proposed method.
international conference on natural computation | 2005
Young-Ran Park; Hyun-Ho Kang; Sang-Uk Shin; Ki-Ryong Kwon
In this paper, we propose a steganographic technique on images that provides high capacity of secret information as well as imperceptibility of stego image. Our method inserts secret data into every pixel of the image and decides the number of insertion bits using the difference value between two pixels adjacent to the target pixel. Therefore, the number of insertion bits in each pixel is dependent on whether the target pixel is included in an edge area or a smooth area. The experiment results show that the proposed method provides more efficient performance than that of the existing methods from the viewpoint of both the insertion amount and the visual measures.
international conference on image processing | 2003
Ki-Ryong Kwon; Seong Geun Kwon; Suk-Hwan Lee; Tae-Su Kim; Kuhn-Il Lee
In this paper, we proposed a watermarking for 3D polygonal meshes using normal vector distribution of each patch. The distribution of norm vector for 3D polygonal mesh is a consistent factor to be robust against various attacks such as affine transform and mesh connectivity altering. Therefore, the proposed algorithm embedded watermark into these consistent normal vectors and equal watermark bit was embedded into each patch of subdivided mesh to have robustness against the partial geometric deformation. Experiment results exhibited the proposed algorithm is robust by extracting watermark bit for various attacked models.
IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences | 2005
Jong-Won Lee; Suk-Hwan Lee; Ki-Ryong Kwon; Kuhn-Il Lee
We proposed 3D-mesh watermarking using CEGI distribution that has robustness against mesh simplification, cropping, vertex randomization, and rotation and which does not need the original model for detection the watermark. The proposed algorithm embeds the watermark bits into the normal vector direction of meshes that are mapped into the cells that have the large magnitude of complex weight in patch CEGIs. The watermark can be detected based on the known center point of each patch and the rank table of the cell in each patch instead of original model. Experimental results verified that the proposed algorithm has robustness against the attacks.
international conference on multimedia and expo | 2004
Ki-Ryong Kwon; Bong-Ju Jang; Eung-Joo Lee; Young Huh
The paper proposes a digital watermarking technique for CAD vertex-based architectural drawings using lines, arcs, and circles to prevent unlawful reproduction and distribution. After extracting lines, arcs, and circles from the drawing, the watermarks are embedded using an adaptive algorithm related to the length of the line, angle of the arc, and radius of the circle. The proposed watermarking scheme is robust to various attacks, like a geometrical transformation. Also, the proposed method satisfies transparency, as the embedding strength is suited to each component. Experimental results confirmed the robustness and invisibility of the embedded watermarks in several architectural drawing conversions
ieee region 10 conference | 2004
Seung-Jin Kim; Suk-Hwan Lee; Kwang-Seok Moon; Woo-Hyun Cho; In-Taek Lim; Ki-Ryong Kwon; Kuhn-Il Lee
We propose the effective video watermarking algorithm to protect the copyright. We use the visible binary image as the watermark. Our watermarking procedure is based on the three-dimensional discrete wavelet transform (3D DWT) and the spread spectrum sequence. We pre-process two watermark images using the mixing and the pseudorandom permutation. After dividing a video sequence into video shots, we perform the 3D DWT. And then, the watermark is embedded into the 3D DWT coefficients considering the robustness and the invisibility. At this time, we use two spread spectrum sequences define as the temporal user key. Experimental results show that the watermarked frames are indistinguishable from the original frames subjectively and the proposed video watermarking algorithm is robust enough against attacks of the low pass filtering, the frame dropping, and the MPEG coding.
international workshop on digital watermarking | 2003
Bong-Ju Jang; Kwang-Seok Moon; Young Huh; Ki-Ryong Kwon
This paper proposed to digital watermarking technique for architectural design 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. Because handlings that are regarded as attacks of watermarked drawing can consist in CAD program, it used AutoCAD 2002 that is common using as a CAD program for experiments. By experimental result, we confirmed robustness and invisibility of embedded watermarks in several conversions of architectural design drawing.
international conference on acoustics, speech, and signal processing | 2006
Tae-Kyu Kim; Jae-Sik Sohn; Suk-Hwan Lee; Ki-Ryong Kwon; Duh-Gyoo Kim
A practical real-time auto-focus algorithm for a digital camera is presented in this paper, and it improves the reliability and speed of the auto-focus process, especially suitable for a 2 mega-pixel high definition camera. The proposed algorithm divides auto-focusing process into several modes and finds the focus by the different control current in the each mode. Additionally, an adaptive step size searching and a hysteresis compensation of the voice coil motor increased searching speed. The experimental result shows the proposed algorithm is faster auto-focusing than conventional algorithm in the VCM camera system
information hiding | 2004
Jae-Gwi Choi; Ji-Hwan Park; Ki-Ryong Kwon
Digital fingerprinting schemes deter people from illegal copying of digital contents by enabling the seller to identify the original buyer of a copy that was redistributed illegally. What is important in designing fingerprinting scheme is to make it more practical and efficient. However, the complexity of existing schemes is too high to be implementable. Recently, oblivious transfer protocol-based schemes to consider practicality were proposed. These are significant in the sense that there are completely specified from a computation point of view and are thus readily implementable. But these schemes have the serious problem that they cannot offer the security of sellers and buyers. In this paper, we first show how to break the existing oblivious transfer-based fingerprinting schemes and then suggest how to make secure fingerprinting schemes against the dishonesty of a sellers and buyers. We use oblivious transfer protocol with two-lock cryptosystem to make it practical and secure. All computations are performed efficiently and the security degree is strengthened in our proposal.