检索结果-内蒙古大学图书馆

IEEE International Symposium on Information Theory

作者： Ba, Demba E. Goyal, Vivek K. MIT Cambridge MA 02139 USA

ISBN: (纸本)9781424413973

This paper introduces a family of integer-to-integer approximations to the Cartesian-to-polar coordinate transformation and analyzes its application to lossy compression. A high-rate analysis is provided for an encoder that first uniformly scalar quantizes, then transforms to "integer polar coordinates," and finally separately entropy codes angle and radius. For sources separable in polar coordinates, the performance (at high rate) is shown to match that of entropy-constrained unconstrained polar quantization-where the angular quantization is allowed to depend on the radius. Thus, for sources separable in polar coordinates but not separable in rectangular coordinates-including certain Gaussian scale mixtures-the proposed system performs better than any transform code. Furthermore, unlike unconstrained polar quantization, integer polar coordinates are appropriate for lossless compression of integer-valued vectors. Combination of integer polar coordinates with integer-to-integer transform coding is also discussed.

关键词： entropy coding Gauss circle problem Gaussian scale mixtures high-rate quantization theory integer-to-integer transforms spherical coordinates transform coding

来源：评论

学校读者我要写书评

暂无评论

Error-resilient decoding of context-based adaptive binary arithmetic codes

引用

Signal, Image and Video Processing 2007年第1期1卷 77-87页

作者： Jeanne, Marion Guillemot, Christine Guionnet, Thomas Pauchet, Florelle IRISA INRIA Campus Universitaire de Beaulieu Rennes 35042 France Envivio Chantepie France

This paper addresses the problem of error-resilient decoding of bitstreams produced by the CABAC (context-based adaptive binary arithmetic coding) algorithm used in the H.264 video coding standard. The paper describes a maximum a posteriori (MAP) estimation algorithm improving the CABAC decoding performances in the presence of transmission errors. Methods improving the re-synchronization and error detection capabilities of the decoder are then described. A variant of the CABAC algorithm supporting error detection based on a forbidden interval is presented. The performances of the decoding algorithm are first assessed with theoretical sources and by considering different binarization codes. They are compared against those obtained with Exp-Golomb codes and with a transmission chain making use of an error-correcting code. The approach has been integrated in an H.264/MPEG-4 AVC video coder and decoder. The PSNR gains obtained are discussed. © 2007 Springer-Verlag London Limited.

关键词： entropy coding Error resilience H.264/MPEG-4 AVC standard Joint source-channel coding Video compression Wireless communication

来源：评论

学校读者我要写书评

暂无评论

Design of high speed cavlc decoder for H.264/AVC

Design of high speed cavlc decoder for H.264/AVC

引用

IEEE Workshop on Signal Processing Systems

作者： Oh, Myungseok Lee, Wonjae Kim, Jaeseok Yonsei Univ Sch Elect & Elect Engn Seoul 120749 South Korea

ISBN: (纸本)9781424412211

In this paper, we propose a high speed CAVLC (Context-based Adaptive Variable Length coding) decoder for H.264/AVC. The previous hardware architectures perform five steps in series to obtain the syntax elements to restore the residual and the codeword length to get next input bitstream (we call it 'valid bits'). Since several cycles are required for the process of getting the valid bits and it has to be iterated several times during CAVLC process, the decoding time is increased. This paper proposes two techniques to reduce the computational cycles for valid bits. One is an improved reduced decoding step from five to four by combining total_coeff step and trailing_ones step into one step. The other is to get the valid bits directly by shifting additional shifter register instead of using controller and accumulator. By adopting these two techniques, the required processing time was reduced by 26% compared with previous architectures. It was designed in a hardware description language and total logic gate count was 14.2k using 0.18um standard cell library.

关键词： CAVLC entropy coding H.2641AVC VLC coding VLSI

来源：评论

学校读者我要写书评

暂无评论

H.264 video stream statistical analysis for post-compression improvements

H.264 video stream statistical analysis for post-compression...

引用

Conference on VLSI Circuits and Systems III

作者： Perez Casanova, J. Hugo Ballester Merelo, Francisco J. Martinez Peiro, Marcos A. Canals Esteve, Josep Univ Politecn Valencia Camino Vera S-N Valencia Spain

ISBN: (纸本)9780819467188

As today's video applications are being requested in many portable end-user devices, and these ones are far capable of holding and processing large amounts of video data, there is a need for bit rate improvement in compression algorithms. The objective of this paper is to propose a hardware based post-compression enhancer situated between the Video coding Layer and the Network Abstraction Layer of H.264. Our research analyzes the resulting bit streams produced by the emerging H.264 standard. The goal is to enhance compression rates by proposing simple post-compression techniques based in symbol's statistics. The CABAC and CAVLC entropy coders used in H.264 work optimally for 1-bit symbols, and the statistical distribution among them is almost the best. Our studies reveal that the bit streams presents similar results for 8-bit symbols, and thus a post-compression using well known byte-based mechanisms will not yield better results;further more, our studies also show that they even degrade the original compression rate. Nevertheless, a non equally distribution using 6-bits symbols in 2046-bits discrete data packets is found, which can be exploited to boost compression. This distribution varies between 5.4% for the most probable symbol and 0.98% for the least probable symbol in average. Again, simple coding a few of the most probable symbols will result in bit rate reduction. A 1-bit compression enhanced used flag penalty must be introduced for each discrete packet. increasing its size in 0.049%.

关键词： fpga vlsi cabac cavlc video compression H.264 entropy coding

来源：评论

学校读者我要写书评

暂无评论

A context modeling scheme for coding of texture refinement information

A context modeling scheme for coding of texture refinement i...

引用

IEEE International Conference on Image Processing (ICIP 2007)

作者： Kirchhoffer, Heiner Marpe, Detlev Wiegand, Thomas Heinrich Hertz Inst Nachrichtentech Berlin GmbH Fraunhofer Inst Telecommun Image Proc Dept Image Commun Grp D-10587 Berlin Germany

ISBN: (纸本)9781424414369

Fidelity scalability involves the refinement of residual texture information. The entropy coding of texture refinement information in the scalable video coding (SVC) extension of H.264/AVC relies on a simple statistical model that is tuned to an encoder-specific way of quantization for generating a single fidelity enhancement layer on top of the backward compatible base layer. For fidelity enhancement layers above the first layer, we demonstrate how and why the current model fails to properly reflect the statistics of texture refinement information. By analyzing the specific properties of the typical quantization process in fidelity scalable coding of SVC, we are able to derive a generic modeling approach for coding of refinement symbols, independent of the specific choice of deadzone parameters and classification rules. Experimental results for a broad range of quantization parameters show averaged bit-rate savings of around 5% (relative to the total bit rate) by using our proposed context modeling approach for a representative set of video sequences in a test scenario including up to three fidelity enhancement layers.

关键词： H.264 AVC SVC entropy coding fidelity scalability

来源：评论

学校读者我要写书评

暂无评论

New Efficient Image Compression Method For Single Sensor Digital Camera Images

<bold>New Efficient Image Compression Method For Single Sens...

引用

7th International Conference on Computational Intelligence and Multimedia Applications

作者： Nallaperumal, Krishnan Christopher, Seldev Vinsley, S. S. Selvakumar, R. K. MS Univ Tirunelveli India CSI Inst Technol Thovalai India Narayanaguru Coll Engg Manjalamoodu India KCE & Technol Virudunagar India

ISBN: (纸本)0769530508

Widely used digital cameras nowadays rise single sensor color filter array (CFA) which captures only one component of a pixel among the three components Red, Green and Blue (RGB). This interleaved RGB valued images are called mosaic images. The mosaic images are of one third of the RGB image's size. The mosaic image can be compressed further to reduce storage. In this paper we propose a new efficient method of lossless compression for color mosaic images. First the mosaic image is transformed by 5/3 forward wavelet transforms, which is best suited for color mosaic data. We also proposed a low complexity Adaptive Context-based Modified Golomb-Rice coding technique to compress the coefficients of the *** lossless compression performance of the proposed method on color mosaic images is arguably the best so far among the existing lossless image codecs.

关键词： 5/3 wavelet transform context quantization entropy coding image compression

来源：评论

学校读者我要写书评

暂无评论

Near-lossless image compression based on maximization of run length sequences

Near-lossless image compression based on maximization of run...

引用

IEEE International Conference on Image Processing (ICIP 2007)

作者： Nasr-Esfahani, E. Samavi, S. Karimi, N. Shiran, S. Isfahan Univ Technol Dept Elect & Comp Engn Esfahan Iran McMaster Univ Hamilton ON Canada

ISBN: (纸本)9781424414369

In this paper an algorithm is proposed which performs near-lossless image compression. For each pixel in a row of the image a group of value-states are considered, which have values close to that of the pixel. A trellis is constructed for every row of the image where the nodes of the trellis are the states of the pixels of that row. The goal of the algorithm is to find a path on this trellis that creates a sequence which can be efficiently coded using run length encoding (RLE). For sections of the pixels of the row that suitable RLE cannot be achieved then minimization of the entropy is employed to complete a path on the trellis. The application of the algorithm to a wide range of standard images shows that the scheme, while having low computational complexity, is competitive with other near-lossless image compression methods.

关键词： image compression run length encoding entropy coding near lossless

来源：评论

学校读者我要写书评

暂无评论

An enhanced robust entropy coder for video codecs based on context-adaptive reversible VLC

An enhanced robust entropy coder for video codecs based on c...

引用

DCC 2007: 2007 Data Compression Conference

作者： Qiang, Wang Debin, Zhao Siwei, Ma Wen, Gao Department of Computer Science and Technology Harbin Institute of Technology Harbin China Institute of Computing Technology Chinese Academy of Sciences Beijing China

No abstract available

ISBN: (纸本)0769527914

No abstract available

关键词： Robustness Video codecs Context modeling Discrete cosine transforms Decoding Resilience Computer science entropy coding Computer errors Information retrieval

来源：评论

学校读者我要写书评

暂无评论

Achieving H.264-like compression efficiency with distributed video coding

Achieving H.264-like compression efficiency with distributed...

引用

Conference on Visual Communications and Image Processing 2007

作者： Milani, Simone Wang, Jiajun Ramchandran, Kannan Univ Padua Dept Informat Engn I-35100 Padua Italy Univ Calif Berkeley Dept Elect Engn & Comp Sci Berkeley CA 94720 USA

ISBN: (纸本)9780819466211

Recently, a new class of distributed source coding (DSC) based video coders has been proposed to enable low-complexity encoding. However, to date, these low-complexity DSC-based video encoders have been unable to compress as efficiently as motion-compensated predictive coding based video codecs, such as H.264/AVC, due to insufficiently accurate modeling of video data. In this work, we examine achieving H.264-like high compression efficiency with a DSC-based approach without the encoding complexity constraint. The success of H.264/AVC highlights the importance of accurately modeling the highly non-stationary video data through fine-granularity motion estimation. This motivates us to deviate from the popular approach of approaching the Wyner-Ziv bound with sophisticated capacity-achieving channel codes that require long block lengths and high decoding complexity, and instead focus on accurately modeling video data. Such a DSC-based, compression-centric encoder is an important first step towards building a robust DSC-based video coding framework.

关键词： distributed video coding H.264/AVC entropy coding

来源：评论

学校读者我要写书评

暂无评论

Optimised compression strategy in wavelet-based video coding using improved context models

Optimised compression strategy in wavelet-based video coding...

引用

IEEE International Conference on Image Processing (ICIP 2007)

作者： Zgaljic, Toni Mrak, Marta Izquierdo, Ebroul Queen Mary Univ London Multimedia & Vis Res Grp London E1 4NS England

ISBN: (纸本)9781424414369

Accurate probability estimation is a key to efficient compression in entropy coding phase of state-of-the-art video coding systems. Probability estimation can be enhanced if contexts in which symbols occur are used during the probability estimation phase. However, these contexts have to be carefully designed in order to avoid negative effects. Methods that use tree structures to model contexts of various syntax elements have been proven efficient in image and video coding. In this paper we use such structure to build optimised contexts for application in scalable wavelet-based video coding. With the proposed approach context are designed separately for intra-coded frames and motion-compensated frames considering varying statistics across different spatio-temporal subbands. Moreover, contexts are separately designed for different bit-planes. Comparison with compression using fixed contexts from Embedded ZeroBlock coding (EZBC) has been performed showing improvements when context modelling on tree structures is applied.

关键词： context modelling entropy coding scalable wavelet-based video coding

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：