• Journal of Broadcast Engineering
• /
• v.7 no.4
• /
• pp.345-354
• /
• 2002

In this paper, we introduce a new scanning method for MPEG-4 AVC based Fine Granular Scalable video coding that can significantly improve the subjective picture quality of a decoded scalable video. The proposed scanning method can guarantee the subjectively improved picture qualify of the decoded scalable video by encoding, transmitting and decoding the visually important region most-preferentially. From the simulation results, it has been found that the proposed scanning method can lead the FGS method to achieve significantly improved picture quality, especially on the region of interests.

• Proceedings of the IEEK Conference
• /
• 2006.06a
• /
• pp.759-760
• /
• 2006

In this paper, The author designed on high speed VLD(Variable Length Decoder) using shift buffer. Variable Length Decoder is received N bit data from input block and decode the input signal using Shifting Buffer, Length Decoder and Symbol Decoder blocks. The inner part of shifting buffer in proposed Variable Length Decoder is filled input data and then operating therefore, the proposed structure can improve the decoded speed. And in this paper we applying pipeline structure therefore data is decoded in every clock.

• Speech Sciences
• /
• v.11 no.4
• /
• pp.17-28
• /
• 2004

In this paper, we propose a statistical approach to improve the performance of spectral quantization of speech coders. The proposed techniques compensate for the distortion in a decoded line spectrum pairs (LSP) vector based on a statistical mapping function between a decoded LSP vector and its corresponding original LSP vector. We first develop two codebook-based probabilistic matching (CBPM) methods based on linear mapping functions according to different assumption of distribution of LSP vectors. In addition, we propose an iterative procedure for the two CBPMs. We apply the proposed techniques to a predictive vector quantizer used for the IS-641 speech coder. The experimental results show that the proposed techniques reduce average spectral distortion by around 0.064dB.

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

• Journal of Korea Multimedia Society
• /
• v.2 no.3
• /
• pp.289-296
• /
• 1999

In this paper, an improved fractal color image decoding method using the data dependence parts and the vector distortion measure is proposed. The vector distortion measure exploits the correlation between different color components. The pixel in RGB color space can be considered as a 30dimensional vector with elements of RGB components. The root mean square error(rms) in RGB color for similarity measure of two blocks R and R' was used. We assume that various parameter necessary in image decoding are stored in the transform table. If the parameter is referenced in decoding image, then decoding is performed by the recursive decoding method. If the parameter is not referenced in decoding image, then the parameters recognize as the data dependence parts and store its in the memory. Non-referenced parts can be decoded only one time, because its domain informations exist in the decoded parts by the recursive decoding method. Non-referenced parts are defined the data dependence parts. Image decoding method using data dependence classifies referenced parts and non-referenced parts using information of transform table. And the proposed method can be decoded only one time for R region decoding speed than Zhang & Po's method, since it is decreased the computational numbers by execution iterated contractive transformations for the referenced range only.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.24 no.7B
• /
• pp.1384-1392
• /
• 1999

A high compression rate is required to transmit video sequences over low bit rate networks such as low bit rate communication channels. When highly compressed videos are transmitted over mobile channels of high error rate, bitstreams corrupted by channel errors are not only difficult to be decoded, but also have fatal effects on the other parts of the bitstreams. In this Paper, we propose an error concealment algorithm for recovering the blocks which can not be decoded due to damaged bitstreams. The proposed error concealment algorithm recovers the damaged blocks using the information of adjacent blocks which are correctly decoded. In the proposed algorithm, the motion vector of the damaged block is estimated using the overlapped block motion compensation(OBMC) and block boundary matching(BBM) techniques. Experiment results show that the proposed algorithm exhibits better performance in PSNR than existing error concealment methods.

• Journal of the Institute of Electronics Engineers of Korea SP
• /
• v.40 no.1
• /
• pp.79-86
• /
• 2003

A new quantization constraint set based on the theory of Projection onto Convex Set(POCS) is proposed to reduce blocking artifact appearing in block-coded images. POCS-based postprocessing for alleviating the blocking artifact consists of iterative projections onto smoothness constraint set and quantization constraint set, respectively. In general, the conventional quantization constraint set has the maximum size of range where original image data can be included, therefore over-blurring of restored image is unavoidable as iteration proceeds. The projection onto the proposed quantization constraint set can reduce blocking artifact as well as maintain the clearness of the decoded image, since it controls adaptively the size of quantization constraint set according to the DCT coefficients. Simulation results using the proposed quantization constraint set as a substitute for conventional quantization constraint set show that the blocking artifact of the decoded image can be reduced by the small number of iterations, and we know that the postprocessed image maintains the distinction of the decoded image.

• Journal of the Korea Institute of Information Security & Cryptology
• /
• v.11 no.6
• /
• pp.15-26
• /
• 2001

Visual cryptography is a simple method in which secret information can be directly decoded in human visual system without any cryptographic computations. When the secret image is scattered to n random shares(slides), this scheme has some week point such as pixel expansion and contrast degradation. Therefore, it is necessary to reduce the pixel expansion and improve the contrast in recovered image. In this paper, we propose a new construction method for (k, n) visual cryptography using the cumulative matrix. In case k is odd, we can construct the cumulative matrix perfectly. For even k, the contrast of special pair in decoded image can be achieved best by permitting multiple contract. The proposed method is more simple than that of S. Droste\`s in construction and the average contrast of decoded image is improved for the most part. Also, we show that the basis matrices depending on the cumulative matrix are able to be applied for the general access structure.

• Journal of Broadcast Engineering
• /
• v.22 no.6
• /
• pp.765-773
• /
• 2017

Ultra-high definition videos, panorama contents, and ultra-wide viewing videos have a huge spatial resolution. However, a whole region of images is not always interesting to viewers due to limitations of system resources and display devices. To allow one or more interesting tiles to be decoded freely without decoding other tiles, this paper introduces a tile-based independent coding method. The propose method restraints motion vectors to be within a tile region shifting motion search area and modifying an initial motion vector. Experiments results show that any desired tile is capable to be decoded independently of other tiles.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.59 no.8
• /
• pp.1489-1496
• /
• 2010

A feed forward differential architecture of analog PRML decoder is investigated to implement on analog parallel processing circuits. The conventional PRML decoder performs the trellis processing with the implementation of single stage in digital and its repeated use. The analog parallel processing-based PRML comes from the idea that the decoding of PRML is done mainly with the information of the first several number of stages. Shortening the trellis processing stages but implementing it with analog parallel circuits, several benefits including higher speed, no memory requirement and no A/D converter requirement are obtained. Most of the conventional analog parallel processing-based PRML decoders are differential architecture with the feedback of the previous decoded data. The architecture used in this paper is without feedback, where error metric accumulation is allowed to start from all the states of the decoding stage, which enables to be decoded without feedback. The circuit of the proposed architecture is simpler than that of the conventional analog parallel processing structure with the similar decoding performance. Characteristics of the feed forward differential architecture are investigated through various simulation studies.