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IEEE Singapore International Conference on Networks

作者： Tan Hak Hwee K. Arichandran Department of Electronics & Communication Engineering Singapore polytechnics Singapore School of Electrical & Electronics Engineering Nanyang Technological University Singapore

A variety of video-phone systems have begun to appear in the consumer market. The quality of the images generated by these systems is severely affected by the bandwidth restriction of the twisted cable pair. Typically, some of these systems operate with a transmission bit rate less than 19.2 kbps. In comparing different systems with respect to image quality, one finds it useful to assess the qualify in terms of descriptors that would represent the subjective assessment more naturally. In this paper, we investigate the possible use of fuzzy set descriptor for the video-phone image. In order to do this, we examine the types of image distortion processes that are obtained in such video-phone systems. We consider three physical effects, namely blurring due to defocusing, blurring due to motion of subject, additive electrical noise in the transmission systems. In addition to the physical distortion processes, we consider distortion due to software artifacts, mainly arising from the use of lossy compression algorithms as well as the associated image blocking effects.

关键词： Videophone systems Additive white noise Image quality Pixel Noise generators Consumer electronics Image generation Additive noise compression algorithms Filters

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Variable step search algorithm for motion estimation

Variable step search algorithm for motion estimation

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IEEE International Symposium on Information Theory

作者： Z.Q. Cai V.N. Tran Department of Communication & Electronic Engineering Royal Melbourne Institute of Technology Melbourne Australia

Motion estimation (ME) is a key technique in interframe coding. It is the basis of most compression algorithms for video compression, such as the CCITT standard H. 261, and MPEG 2. The performance of ME is decided by two factors: (1) the estimation exactitude; and (2) the computational load. The full search algorithm is the optimal one for the first factor, but it requires extensive computations. To reduce the computational complexity, many efficient search algorithms have been proposed. The one step at a time search (OSATS) is the second most efficient algorithm, but it becomes inefficient when the search window is greater than 4 pels/frame. The aim of this paper is to overcome this disadvantage.

关键词： Motion estimation Variable structure systems Australia compression algorithms Video compression Computational complexity Computational modeling Video coding Measurement standards Displacement measurement

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Video coding using 3 dimensional DCT and dynamic code selection

Video coding using 3 dimensional DCT and dynamic code select...

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Data compression Conference (DCC)

作者： M. Bauer K. Sayood Department of Electrical Engineering University of Nebraska Omaha Lincolnshire NE USA

Summary only given. We address the quality issue, and present a method for improved coding of the 3D DCT coefficients. Performance gain is achieved through the use of dynamically selected multiple coding algorithms. The resulting performance is excellent giving a compression ratio of greater than to 100:1 for image reproduction. The process consists of stacking 8 frames and breaking the data into 8/spl times/8/spl times/8 pixel cubes. The three dimensional DCT is applied to each cube. Each cube is then scanned in each dimension to determine if significant energy exists beyond the first two coefficients. Significance is determined with separate thresholds for each dimension. A single bit of side information is transmitted for each dimension of each cube to indicate whether more than two coefficients will be transmitted. The remaining coefficients of all cubes are reordered into a linear array such that the elements with the highest expected energies appear first and lower expected energies appear last. This tends to group coefficients with similar statistical properties for the most efficient coding. Eight different encoding methods are used to convert the coefficients into bits for transmission. The Viterbi algorithm is used to select the best coding method. The cost function is the number of bits that need to be sent. Each of the eight coding methods is optimized for a different range of values.

关键词： Video coding Discrete cosine transforms Video compression Biomedical imaging HDTV compression algorithms Image coding Back Bit rate Performance gain

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A single-chip lossless data compressor

A single-chip lossless data compressor

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International Symposium on VLSI Technology, Systems and Applications

作者： B.W.Y. Wei J.L. Chang V.I. Leong Department of Electrical Engineering College of Engineering San Jose State University Foundation San Jose CA USA San Jose State University San Jose CA US Dept. of Electr. Eng. San Jose State Univ. CA USA

This paper describes a single-chip compressor implementing a combined LZSS and Huffman compression algorithm. The chip uses a 512-byte on-chip CAM/SRAM for storing the most recent characters which the incoming string is compared against and referenced to. The reference entries are then Huffman coded using a transposition implementation. The chip in 1.2 /spl mu/m CMOS is 0.9 cm/sup 2/ with a clock speed of 40 ns. With a compression ratio of above 2.1, it performs compression/decompression at a rate of 32 bytes per 33 clock cycles.

关键词： Dictionaries Decoding Algorithm design and analysis Codecs Clocks Testing Huffman coding Educational institutions Data engineering compression algorithms

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Tele-action objects for an active multimedia system

Tele-action objects for an active multimedia system

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IEEE International Conference on Multimedia Computing and Systems (ICMCS)

作者： Hui-Jung Chang Tai-Yuan Hou Arding Hsu Shi-Kuo Chang Department of Computer Science University of Pittsburgh Pittsburgh PA USA Siemens Corporate Research Inc. Princeton NJ USA

ISBN: (纸本)081867105X

We present the concept of tele-action objects (TAOs), which possess private knowledge specific to the object instances. The user can create and modify the private knowledge of a tele-action object, so that the tele-action object will automatically react to certain events to pre-perform operations for generating timely response, improving operational efficiency and maintaining consistency. Moreover tele-action objects also possess a hypergraph structure leading to the effective presentation and efficient communication of multimedia information. The active multimedia system (AMS) is provided to manipulate and maintain the TAOs. The user interface and the system architecture for the AMS are described. A multimedia mail system is implemented to illustrate the usefulness of tele-action objects. Finally, we discuss the advantages of the proposed approach and future research.

关键词： Multimedia systems Delay Postal services Object oriented modeling Information systems Computer science Educational institutions Multimedia communication compression algorithms Algorithm design and analysis

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Queuing models of synchronous compressors

Queuing models of synchronous compressors

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Data compression Conference (DCC)

作者： M.S. Moellenhoff M.W. Maier Dynetics Inc. Huntsville AL USA ECE Department University of Alabama Huntsville Huntsville AL USA

Summary form only given. In synchronous compression, a lossless data compressor attempts to equalize the rates of two synchronous communication channels. Synchronous compression is of broad applicability in improving the efficiency of internetwork links over public digital networks. The most notable features of the synchronous compression application are the mixed traffic it must tolerate and the rate buffering role played by the compression processor. The resulting system can be modeled in the time domain by queuing methods. The performance of a compression algorithm in this application is governed by the interplay of its ultimate compression ratio, its computational efficiency, and the distribution function of its instantaneous consumption rate of the source. The queuing model for synchronous compression represents the compressor as the server fed by a single queue. We describe the basic model, develop the required basic queuing theory, look at service time statistics, and compare to simulation. We develop the queuing model for synchronous compression and relate it to theoretical and empirical properties of queuing systems and Lempel-Ziv compression algorithm performance. We illustrate that synchronous compression simulations are in agreement with the predictions of queuing theory. In addition, we observe various interesting properties of match length distributions and their impact on compression in the time-domain.

关键词： Compressors Queueing analysis compression algorithms Communication channels IP networks Telecommunication traffic Traffic control Computational efficiency Distribution functions Statistical distributions

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Statistical characteristics and multiplexing of MPEG streams

Statistical characteristics and multiplexing of MPEG streams

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IEEE Annual Joint Conference: INFOCOM, IEEE Computer and Communications Societies

作者： M. Krunz R. Sass H. Hughes Department of Electrical Engineering Michigan State University East Lansing MI USA Department of Computer Science Michigan State University East Lansing MI USA

This paper presents a study of the statistical characteristics and multiplexing of variable-bit-rate (VBR) MPEG-coded video streams. Our results are based on 23 minutes of video obtained from the entertainment movie, The Wizard of Oz. The experimental setup which was used to capture, digitize, and compress the video stream is described. Although the study is conducted at the frame level (as opposed to the slice level), it is observed that the inter-frame correlation structure for the frame-size sequence involves complicated forms of pseudo-periodicity that are mainly affected by the compression pattern of the sequence. A simple model for an MPEG traffic source is developed in which frames are generated according to the compression pattern of the original captured video stream. The number of cells per frame is fitted by a lognormal distribution. Simulations are used to study the performance of an ATM multiplexer for MPEG streams.

关键词： Video compression Streaming media Transform coding Traffic control Video sequences Telecommunication traffic Motion pictures Asynchronous transfer mode compression algorithms Motion compensation

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IMAGE compression VIA IMPROVED QUADTREE DECOMPOSITION algorithms

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IEEE TRANSACTIONS ON IMAGE PROCESSING 1994年第2期3卷 207-215页

作者： SHUSTERMAN, E FEDER, M Department of Electrical Engineering-Systems Faculty of Engineering Tel-Aviv University Tel-Aviv Israel

Quadtree decomposition is a simple technique used to obtain an image representation at different resolution levels. This representation can be useful for a variety of image processing and image compression algorithms. This paper presents a simple way to get better compression performances (in MSE sense) via quadtree decomposition, by using: Near to optimal choice of the threshold for quadtree decomposition. Bit allocation procedure based on the equations derived from rate-distortion theory. The rate-distortion performance of the improved algorithm is calculated for some Gaussian field, and it is examined vie simulation over benchmark gray-level images. In both these cases, significant improvement in the compression performances is shown.

关键词： Image coding Image segmentation Rate-distortion Image representation Image resolution Image processing Bit rate compression algorithms Equations Image sequences

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SCALABLE compression FOR IMAGE BROWSING

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IEEE TRANSACTIONS ON CONSUMER ELECTRONICS 1994年第3期40卷 394-404页

作者： JAIN, A PANCHANATHAN, S Department of Electrical Engineering University of Ottawa Ottawa ONT Canada

In this paper, we present scalable compression algorithms for image browsing. Recently, the International Standards Organization (ISO) has proposed the JPEG standard for still image compression. JPEG standard not only provides the basic feature of compression (baseline algorithm) but also provides the framework for reconstructing images in different picture qualities and sizes. These features are referred to as SNR and spatial scalability, respectively. SNR scalability and spatial scalability can be implemented using the progressive and hierarchical modes in the JPEG standard. In this paper, we implement and investigate the performance of the progressive and hierarchical coding modes of the JPEG standard and compare their performance with the baseline algorithm,

关键词： JPEG compression algorithms browsing Scalability

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algorithms and architectures for hierarchical compression of video

Algorithms and architectures for hierarchical compression of...

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International Conference on Application Specific Array Processors

作者： M. Vishwanath Computer Science Lab Xerox-PARC Palo Alto CA USA

The paper addresses the problem of collaborative video over "heterogeneous" networks. Current standards for video compression are not designed to deal with this problem. We define an additional set of metrics (ie., in addition to the standard rate versus distortion measure) to evaluate compression algorithms for this application. We also present an efficient algorithm and corresponding architectures for video compression in such an environment. The algorithm is a unique combination of the discrete wavelet transform and hierarchical vector quantization. It is unique in that both the encoder and the decoder are implemented with only table lookups. This makes both the software and hardware implementations very efficient and cheap.< >

关键词： Video compression Discrete wavelet transforms Collaboration Measurement standards Rate distortion theory Distortion measurement compression algorithms Computer architecture Vector quantization Decoding

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