• Journal of the Institute of Electronics Engineers of Korea SP
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• v.39 no.6
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• pp.575-584
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• 2002

This paper presents a novel DCT-based embedded zero-tree coding and optimal bit allocation algorithm for image sequence coding. In order to fully utilize the structure of the conventional standard coding algorithm and improve the coding efficiency, motion estimation and compensation(ME/MC)-DCT hybrid coding structure and a modified zero-tree coding algorithm are applied. After the rearrangement DCT coefficients into pyramidal structure according to their significance on the decoded image quality, the modified embedded zero-tree coding is performed on layered coefficients. Moreover, for a given overall bit rates, a new optimal bit control scheme is proposed to achieve the best decoded image quality in the consecutive frames. The rate control scheme can also provide the equal quality of decoded image with the control of bit rate and distortion for each frame. The various simulation results are provided to evaluate the coding performance of the proposed scheme.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.10B
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• pp.1093-1103
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• 2009

In this paper, we propose a new depth map based distributed multi-view video coding algorithm through an efficient side information generation. A distributed video coding scheme corrects errors between an original image and side information generated at a decoder by using channel coding techniques. Therefore, the more accurate side information is generated, the better performance of distributed video coding scheme is achieved. In the proposed algorithm, a distributed video coding scheme is applied to multi-view video coding based on depth map. Side information is also generated from images of adjacent views through 3D warping by using a depth map and is also combined with MCTI(motion compensated temporal interpolation) which uses images on a temporal axis, and 3D warping. Experimental results show that side information generated by using the proposed algorithm has 0.97dB better average PSNR compared with using MCTI and 3D warping separated. In addition, 8.01% of average bit-rate has been decreased while the same PSNR in R-D curves is kept.

• Journal of Electrical Engineering and Technology
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• v.9 no.5
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• pp.1762-1773
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• 2014

In this paper, a distributed image coding scheme for multi-view video through an efficient generation of side information is proposed. A distributed video coding technique corrects the errors in the side information, which is generated with the original image, by using the channel coding technique at the decoder. Therefore, the more correct the generated side information is, the better the performance of distributed video coding. The proposed technique is to apply the distributed video coding schemes to the image coding for multi-view video. It generates side information by selectively and efficiently using both 3-dimensional warping based on the depth map with spatially adjacent frames and motion-compensated temporal interpolation with temporally adjacent frames. In this scheme the difference between the adjacent frames, the sizes of the motion vectors for the adjacent blocks, and the edge information are used as the selection criteria. From the experiments, it was observed that the quality of the side information generated by the proposed technique was improved by the average peak signal-to-noise ratio of 0.97dB than the one by motion-compensated temporal interpolation or 3-dimensional warping. The result from analyzing the rate-distortion curves revealed that the proposed scheme could reduce the bit-rate by 8.01% on average at the same peak signal-to-noise ratio value, compared to previous work.

• The Journal of the Acoustical Society of Korea
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• v.27 no.1
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• pp.18-25
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• 2008

In this paper, new lossless coding method of spectral coefficients for audio codec is proposed. Conventional lossless coder uses Huffman coding utilizing the statistical characteristics of spectral coefficients, but does not provide the high coding efficiency due to its simple structure. To solve this limitation, new lossless coding scheme with better performance is proposed that consists of bit-plane transform and run-length coding. In the proposed scheme, the spectral coefficients are first transformed by bit-plane into 1-D bit-stream with better correlative properties, which is then coded intorun-length and is finally Huffman coded. In addition, the coding performance is further increased by applying the proposed bit-plane coding selectively to each group, after the entire frequency is divided into 3 groups. The performance of proposed coding scheme is measured in terms of theoretical number of bits based on the entropy, and shows at most 6% enhancement compared to that of conventional lossless coder used in AAC audio codec.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39A no.11
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• pp.625-636
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• 2014

In this paper, we propose a new embedded image compression scheme which uses rate-distortion optimized block coding of wavelet coefficients. Unlike to previous works in which set-partition or block-partition is performed according to the magnitude of wavelet coefficients, the proposed scheme achieves rate-distortion optimization by sorting wavelet coefficients or blocks according to their expected rate-distortion slope. At the same time, it performs the optimized block-partition coding using the expected rate-distortion slope of blocks. The proposed scheme also uses various relationship of wavelet coefficients for the entropy coding. Experimental results demonstrate that the proposed image compression scheme provides better overall performance than the existing embedded coding schemes such as SPIHT and EBCOT, in which the PSNR gains of the proposed scheme are about 0.11~1.16dB and -0.18~0.52dB, respectively.

• Journal of Biomedical Engineering Research
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• v.18 no.4
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• pp.349-356
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• 1997

In this paper, we propose the lossless coding: scheme for progressive transmission of medical images. The input image is decomposed by the proposed fast adaptive subband decomposition method which is suited for a lossless coding. The decomposed images are coded by an arithmetic coder with two conditioning pixels, and the conditioning pixels are selected differently according to the property of the subbands. The conditioning contexts are usually quantized to reduce the conditional state, and the optimization method of quantization is proposed For the purpose of improving compression ratio in this paper. The proposed lossless coding scheme provides the asymmetric structure of cosec and results in better compression ability than the JPEC lossless coding[ 1 ].

• Journal of KIISE:Computing Practices and Letters
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• v.10 no.4
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• pp.309-318
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• 2004

This paper proposes the H.264-based selective fine granular scalable (FGS) coding scheme that selectively uses the temporal prediction data in the enhancement layer. The base layer of the proposed scheme is basically coded by the H.264 (MPEG-4 Part 10 AVC) visual coding scheme that is the state-of-art in codig efficiency. The enhancement layer is basically coded by the same bitplane-based algorithm of the MPEG-4 (Part 2) fine granular scalable coding scheme. In this paper, we introduce a new algorithm that uses the temproal prediction mechanism inside the enhancement layer and the effective selection mechanism to decide whether the temporally-predicted data would be sent to the decoder or not. Whenever applying the temporal prediction inside the enhancement layer, the temporal redundancies may be effectively reduced, however the drift problem would be severly occurred especially at the low bitrate transmission, due to the mismatch bewteen the encoder's and decoder's reference frame images. Proposed algorithm selectively uses the temporal-prediction data inside the enhancement layer only in case those data could siginificantly reduce the temporal redundancies, to minimize the drift error and thus to improve the overall coding efficiency. Simulation results, based on several test image sequences, show that the proposed scheme has 1∼3 dB higher coding efficiency than the H.264-based FGS coding scheme, even 3∼5 dB higher coding efficiency than the MPEG-4 FGS international standard.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.9
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• pp.8-12
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• 2008

In this paper, we proposes a D-STTD(Double-Space Time Transmit Diversity) communication system with AMC scheme and analyzes its performance using simulation experiments. The AMC scheme selects an optimal channel coding rate and modulation scheme based on the channel response data for signal transmission, creating a balance between error rate and throughput to improve the overall system throughput and transmission quality. The D-STTD scheme complements the conventional STTD(Space Time Transmit Diversity) scheme, yielding about twice the throughput. The simulation results show that the probability of selecting a high MCS(Modulation and Coding Scheme) level increased as the SNR(Signal to Noise Ratio) improved. Furthermore, the D-STTD communication system with AMC scheme provided a more uniform throughput distribution throughout the entire SNR range compared to its counterpart which did not apply AMC scheme. Also, the maximum throughput of the D-STTD communication system with AMC scheme was twice that of a conventional AMC communication system or a STTD communication system with AMC scheme.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.5 no.5
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• pp.1013-1027
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• 2011

In this paper we propose ATCS, a practical TCP protocol coding scheme based on network coding for satellite IP networks. The proposal is specially designed to enhance TCP performance over satellite networks. In our scheme, the source introduces a degree of redundancy and transmits a random linear combination of TCP packets. Since the redundant packets are utilized to mask packet loss over satellite links, the degree of redundancy is determined by the link error rates. Through a simple and effective method, ATCS estimates link error rates in real time and then dynamically adjusts the redundant factor. Consequently, ATCS is adaptable to a wide range of link error rates by coding TCP segments with a flexible redundancy factor. Furthermore, the scheme is compatible with traditional TCP variants. Simulation results indicate that the proposal improves TCP performance considerably.

• Journal of Satellite, Information and Communications
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• v.6 no.2
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• pp.66-71
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• 2011

This paper evaluates the performance and effectiveness of a layered coding scheme for an integrated mobile satellite systems, where the main target services are multimedia broadcasting and multicasting services (MBMS). In this integrated system, the satellite and complementary ground components (CGC) cooperate to provide high quality services. A layered coding scheme is a receiver driven adaptive schemes which adapts to the channel condition at the receiver. In this paper, we introduce a layered turbo coding scheme, and evaluates the performance in various scenarios, and discuss its effectiveness. The demonstrated results in the paper can be utilized in order to design an efficient integrated mobile satellite system, in the future.