• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.2C
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• pp.132-140
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• 2007

In this paper, we proposed a new technique to encode and decode the digital hologram. Since the digital hologram (or fringe pattern) is generated by interference of light, it has much different property from natural 2D (2 dimensional) images. First, we acquisite optical-sensed or computer-generated hologram by digital type, and then extract a chrominance component. The extracted digital hologram for coding is separated into segments to use multi-view properties. The segmented hologram shows the similar characteristics with picturing an object with 2D cameras in various point of view. Since fringe pattern is visually observed like as noise, we expect that the fringe pattern has poor coding efficiency. To obtain high efficiency, the segment is transformed with DCT (Discrete Cosine Transform) which resembles hologram generation process with high performance. Each transformed segment passes the 3D scanning process according to time and spatial correlation, and is organized into a video stream. Since the segment which correspond to frame of a video stream consists of the transformed coefficients with wide range of value, it is classified and re-normalized. Finally it is compressed with coding tools. The proposed algorithm illustrated that it has better properties for reconstruction of 16 times higher compression rate than the previous researches.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.8B
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• pp.1518-1531
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• 1999

The reconstructed images from highly compressed MPEG or H.263 data have noticeable image degradations, such as blocking artifacts near the block boundaries, corner outliers at cross points of blocks, and ringing noise near image edges, because the MPEG or H.263 quantizes the transformed coefficients of 8$\times$8 pixel blocks. A post-processing algorithm has been proposed by authors to reduce quantization effects, such as blocking artifacts, corner outliers, and ringing noise, in MPEG-decompressed images. Our signal-adaptive post-processing algorithm reduces the quantization effects adaptively by using both spatial frequency and temporal information extracted from the compressed data. The blocking artifacts are reduced by one-dimensional (1-D) horizontal and vertical low pass filtering (LPF), and the ringing noise is reduced by two-dimensional (2-D) signal-adaptive filtering (SAF). A comparison study of the subjective quality evaluation using modified single stimulus method (MSSM), the objective quality evaluation (PSNR) and the computation complexity analysis between the signal-adaptive post-processing algorithm and the MPEG-4 VM (Verification Model) post-processing algorithm is performed by computer simulation with several MPEG-4 image sequences. According to the comparison study, the subjective image qualities of both algorithms are similar, whereas the PSNR and the comparison complexity analysis of the signal-adaptive post-processing algorithm shows better performance than the VM post-processing algorithm.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.40 no.6
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• pp.48-57
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• 2003

In this paper, An 8${\times}$l ID-IDCT processor with adder-based distributed arithmetic(DA) and bit-serial method Is presented. To reduce hardware cost and to improve operating speed, the proposed 8${\times}$1 ID-IDCT used the bit-serial method and DA method. The transform of coefficient equation results in reduction in hardware cost and has a regularity in implementation. The sign extension computation method reduces operation clock. As a result of logic synthesis, The gate count of designed 8${\times}$1 1D-IDCT is 17,504. The sign extension processing block has gate count of 3,620. That is 20% of total 8${\times}$1 ID-IDCT architecture. But the sign extension processing block improves more than twice in throughput. The designed IDCT processes 50Mpixels per second and at a clock frequency of 100MHz.

• Journal of Korea Society of Industrial Information Systems
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• v.12 no.1
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• pp.39-45
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• 2007

In this paper, we present a new postprocessing algorithm using interpolation and signal adaptive filter according to the each block characteristic which is acquired in block classification process. We applied blocking artifact reduction algorithm for four neighbor low frequency block and ringing artifacts is removed with preserving edges by applying a signal adaptive filter in high frequency block based on edge map. The computer simulation results confirmed a better performance by the proposed method in both the subjective and objective image qualities.

• Journal of Advanced Navigation Technology
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• v.11 no.1
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• pp.105-111
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• 2007

This paper is concerned with fuzzy inference-based optimal sub-bands decision scheme which is to be embedded the watermark. It concentrated not only on design of fuzzy inference algorithm but also on human visual parameters (HVP), such as contrast sensitivity, texture degree. In the first, such human visual parameters as contrast sensitivity, texture degree as well as statistical characteristics are involved to select the optimal coefficients region. Secondly, fuzzy if - then rule which can be able to adapt the wide variety of environments is developed. The performance of proposed approach is evaluated with respect to the imperceptibility and correctness of watermark. According to some experimental results, contrast sensitivity function is superior in smooth image. On the other hand, statistical characteristics provide good results in rough images.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.6 no.2
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• pp.65-70
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• 2013

In this paper, we proposed color image watermarking using human visual system. A watermark is embedded by transforming a color image of RGB coordinate into a color image of HSI coordinate with considering that chromatic components are less sensitive than achromatic components. Watermark is embedded in the frequency domain of the chromatic channels by using discrete cosine transform. Watermark is extracted from watermarked image by using inverse discrete cosine transform. To verify the proposed method, a standard image and a fingerprint image are used for the original image and the watermark image, respectively. Simulation results are satisfied with invisibility and robustness from attacks as image compression.

• Proceedings of the Korea Information Processing Society Conference
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• 2003.05b
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• pp.931-934
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• 2003

본 논문에서는 동영상 내용 기반 검색을 위한 표준 인덱스인 color layout descriptor(CLD)에 기반한 새로운 장면전환검출 방법을 제안한다. 제안한 방법은 입력 영상을 $8{\times}8$ 블록으로 나누고, 그 블록을 대표하는 대표컬러를 선택하여 DCT 변환 후 추출된 DC, AC 계수에 가중치를 부여한 다음 슬라이딩 윈도우를 적용시켜 장면 전환을 검출한다. 이러한 방법은 영상의 전체적인 특성과 국부적인 특성을 동시에 반영하므로, 조명변화나 물체의 움직임에 민감했던 기존 대표적인 방법인 히스토그램 기반 방법과 에지 변화율을 이용한 방법들이 가지는 문제점을 보완할 수 있다. 또한 제안한 방법은 비디오 검색을 위한 MPEG-7 의 검색 서술자 중의 하나인 CLD를 이용하는데 이러한 CLD 는 컬러의 공간적 분포를 잘 설명하므로 MPEG-7 을 위한 검색 서술자에 적합한 장면전환검출 및 검색이 이루어질 수 있다. 제안한 방법을 실험한 결과 기존의 방법보다 장면전환 검출율이 높게 나타났다.

• Journal of Broadcast Engineering
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• v.14 no.1
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• pp.36-43
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• 2009

Recently, the structural similarity (SSIM) index metric is proposed. In the present paper, a new framework, which is called visual SSIM (VSSIM), is proposed by incorporating crucial human factors into the SSIM. The human factors are foveation, luminance, frequency and motion information. The performance of VSSIM is evaluated by subjective quality test compliant with the Video Quality Expert Group (VQEG) multimedia group test plan. It shows that the visual SSIM is more correlated with the subjective quality result than the conventional SSIM.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.9 no.5
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• pp.1019-1024
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• 2005

MPEG-2 achieves high compression radio, by exploiting the temporal and spatial correlations in real image sequence, using the motion compensated prediction and the transform coding, respectively. However, as the image sequence is more highly compressed, the encoded bitstream becomes more vulnerable to transmission error over the noisy channels. Furthermore, er개rs in the headers are fatal to decoding processes, because the header parameters in the video coding standard include a lot of important information connected to the syntax elements, fables, and decoding process. In this paper, we propose a new error resilience method using LSB coding for header parameters in MPEG-2 coded video transmissions. The experimental results for football and susie video sequence demonstrate that the proposed error resilience method for header parameters in MPEG-2 bitstream has good performance.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.3C
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• pp.387-397
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• 2004

The wavelet transform providing both of the frequency and spatial information of an image is proved to be very much effective for the compression of images, and recently lot of studies on coding algorithms for images decomposed by the wavelet transform together with the multi-resolution theory are going on. This paper proposes a quadtree decomposition method of image compression applied to the images decomposed by wavelet transform by using the correlations between pixels and '0'data grouping. Since the coefficients obtained by the wavelet transform have high correlations between scales and high concentrations, the quadtree method can reduce the data quantity effectively. the experimental infrared image with 256${\times}$256 size and 8〔bit〕, was used to compare the performances of the existing and the proposed compression methods.