• Proceedings of the IEEK Conference
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• 1999.11a
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• pp.491-494
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• 1999

Introduction of digital communication network such as Integrated Services Digital Networks(ISDN) and digital storage media have rapidly developed. Due to a large amount of image data, compression is the key techniques in still image and video using digital signal processing for transmitting and storing. Digital image compression provides solutions for various image applications that represent digital image requiring a large amount of data. In this paper, the proposed DWT(Discrete Wavelet Transform) filter bank is consisted of simple architecture, but it is efficiently designed that a user obtain a wanted compression rate as only input parameter. If it is implemented by FPGA chip, the designed encoder operates in 12MHz.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.6 no.3
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• pp.464-469
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• 2002

In this research, nonvisibility and robustness of image watermarking mixed Key and Logo method were evaluated. The role of the Key was performed by a personal ID of a copyrighter and the logo images were used as the watermark. The standard image of Lena was used for experimental image and binary images of `Park'with size 32${\times}$32 and 64${\times}$64 were used for the watermark, respectively In order to evaluate nonvisibility of the proposed watermarking scheme, PSNR(Peak Signal to Noise Ratio) of the watermarked image was obtained and for robustness reconstructive rates of the reconstructed watermark were obtained from the watermarked image with image transformation of JPEG lossy compression. The experimental results show that nonvisibility is excellent as PSNR of the watermarked image is 93.75dB and the reconstructive rates of the case of 322${\times}$32 watermark was better than the case of the 64${\times}$64 watermark; average 5.9%, 13.9%, 6.5%, and 4.2% in the case of scale-down rates, rotational rates, impulse noise power density, and JPEG lossy compression rates, respectively.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.48 no.2
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• pp.1-10
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• 2011

In this paper, we propose the algorithm for the AR(Augmented Reality) system, which is robust to the brightness change of light. In the proposed method, the histogram specification is achieved using the sample histogram, obtained from the frames in which the target objects could be detected successful. And When the object key-points couldn't be detected by the displacement of camera positions, the positions of non-detected key-points ware estimated using the linear KF(Kalman Filter). When the proposed algorithm is applied in the AR systems, the object key-points can be detected three times as much as the existing others. In addition, to prove the more efficiency of the proposed algorithm, we implemented the AR game, and could know that the performance is the more advanced than the others. The proposed algorithm can be used for the AR environments, which high efficiency is required such as the AR game, or the implementation of AR systems which are robust to the change of lights, etc.

• Journal of the Korea Society of Computer and Information
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• v.10 no.2 s.34
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• pp.39-47
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• 2005

This paper proposes and analyzes the MAC(Message Authentication Code) algorithm that is used for the transition integrity and the entity authentication of message. The MAC algorithm uses the DES algorithm which has 64-bit block and 56-bit key and we compare the security according to 64-bit and 32-bit length of MAC value. Moreover, we use the SEED algorithm which has 128-bit block and 128-bit key and compare the security according to 128-bit and 64-bit length of MAC value. We analyze the security the forgery attack according to length of message and length of MAC value. this paper, a coarse-to-fine optical flow detection method is proposed. Provided that optical flow gives reliable approximation to two-dimensional image motion, it can be used to recover the three-dimensional motion. but usually to get the reliable optical flows are difficult. The proposed algorithm uses Horn's algorithm (or detecting initial optical flow, then Thin Plate Spline is introduced to warp a image frame of the initial optical flow to the next image frame. The optical flow for the warped image frame is again used iteratively until the mean square error between two image sequence frames is lowered. The proposed method is experimented for the real moving Picture image sequence. The proposed algorithm gives dense optical flow vectors.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2002.05a
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• pp.598-601
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• 2002

In this research, robustness of image watermarking mixed Key and Logo scheme was evaluated. A personal ID of a copyrighter was key and watermark was logo image. The standard images of Baboon, Cameraman and Lena were used for experimental images, binary image‘Park’of 32$\times$32 and 64$\times$64 size were used for the watermark image, respectively. for robustness evaluation of the watermark, reconstructive rates of the watermark were obtained from images inserted watermark with image transformation or JPEG lossy compression. The experimental results show that the reconstructive rates of the case of 32$\times$32 watermark was better than the case of the 64$\times$64 watermark; average 5.9%, 13.9%, 6.5%, and 4.2% in the case of scale-down rates, rotational rates, impulse noise power density, and JPEG lossy compression rates, respectively.

• The KIPS Transactions:PartC
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• v.9C no.1
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• pp.1-8
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• 2002

Digital image watermarking is a technique for the purpose of protecting the ownership of the image by embedding proprietary watermarks in a digital image. It is required for the digital image watermarking scheme to pursue the robustness against water marking attacks and the perceptual Invisibility more than usual in steganography area, to guarantee not a hidden watermarking algorithm but the publicity of water-marking algorithm details and hidden use of key, which can protect the unauthorized user access from detection. In this paper we propose a new copyright watermarking scheme, which is barred on one-way hash functions using ElGamal functions and modular operations. ElGamal functions are widely used in cryptographic systems. Our watermarking scheme is robust against LSB(least significant bit) attacks and gamma correction attack, and also perceptually invisible. We demonstrate the characteristics of our proposed watermarking scheme through experiments. It is necessary to proceed as the future work the algorithm of achieving at the same time both the pseudo-randomness for the steno-key generation and the asymmetric-key generation.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.6 no.1
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• pp.426-445
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• 2012

Conventional rate control (RC) schemes for H.264 video coding usually regulate output bit rate to match channel bandwidth by adjusting quantization parameter (QP) at fixed full frame rate, and the passive frame skipping to avoid buffer overflow usually occurs when scene changes or high motions exist in video sequences especially at low bit rate, which degrades spatial-temporal quality and causes jerky effect. In this paper, an active content adaptive frame skipping scheme is proposed instead of passive methods, which skips subjectively trivial frames by structural similarity (SSIM) measurement between the original frame and the interpolated frame via motion vector (MV) copy scheme. The saved bits from skipped frames are allocated to coded key ones to enhance their spatial quality, and the skipped frames are well recovered based on MV copy scheme from adjacent key ones at the decoder side to maintain constant frame rate. Experimental results show that the proposed active SSIM-based frameskip scheme acquires better and more consistent spatial-temporal quality both in objective (PSNR) and subjective (SSIM) sense with low complexity compared to classic fixed frame rate control method JVT-G012 and prior objective metric based frameskip method.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.12
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• pp.4533-4551
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• 2014

The effective extraction of key frames from a video stream is an essential task for summarizing and representing the content of a video. Accordingly, this paper proposes a new and fast method for extracting key frames from a compressed video. In the proposed approach, after the entire video sequence has been segmented into elementary content units, called shots, key frame extraction is performed by first assigning the number of key frames to each shot, and then distributing the key frames over the shot using a probabilistic approach to locate the optimal position of the key frames. Moreover, we implement our proposed framework in Android to confirm the validity, availability and usefulness. The main advantage of the proposed method is that no time-consuming computations are needed for distributing the key frames within the shots and the procedure for key frame extraction is completely automatic. Furthermore, the set of key frames is independent of any subjective thresholds or manually set parameters.

• Proceedings of the IEEK Conference
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• 1999.11a
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• pp.589-592
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• 1999

Matching is a key problem in computer vision, image analysis and pattern recognition. In this paper a multiscale image matching algorithm by wavelet local extrema is proposed. This algorithm is based on the multiscale wavelet transform of the curvature which can utilize both the information of local extrema positions and magnitudes of transform results. This method has advantages in computational cost to a single scale image matching. It is also rotation-, translation-, and scale-independent image matching method. This matching can be used for the recognition of occluded objects.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.27 no.5
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• pp.1059-1068
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• 2017

Even though BioHashing scheme can effectively extract binary string key from analog biometrics templates, it shows lower performance in stolen-token scenario due to dependency of the token. In this paper, to overcome this limitation, we suggest a new method of generating security key from face image and user intervention. Using BioHashing and GPT schemes, our scheme can adjust dependency of PIN for user authentication and generate robust key with sufficient length. We perform various experiments to show performance of the proposed scheme.