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Wavelet Applications III Conference

作者： Uhl, A SALZBURG UNIV RES INST SOFTWARETECHNOLA-5020 SALZBURGAUSTRIA

ISBN: (纸本)081942143X

In this paper a new approach for adaptive wavelet image coding is introduced. Based on an adaptive quadtree image-block partition (similar to fractal coding) the different image blocks may be compressed independently in an adaptive manner. In order to adapt to local image statistics and features we present several possibilities of how to optimize the transform part of a wavelet image block-coder. Additionally we present a parallel algorithm suitable for MIMD architectures for efficient implementation of the proposed method. Finally experimental results concerning coding efficiency and execution time on a cluster of workstations are described.

关键词： image compression wavelets parallel algorithms adaptive coding

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Transform coding using adaptive bases and quantization

Transform coding using adaptive bases and quantization

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IEEE International Conference on Image Processing

作者： V.K. Goyal J. Zhuang M. Vetterli C. Chan Department of Electrical Engineering and Computer Science University of California Berkeley USA

This paper considers the problem of universal transform coding based on estimating the Karhunen-Loeve transform from quantized data. The use of quantized data in the estimation allows the encoder and decoder to maintain the same state without any side information. A theorem is presented that proves, under certain conditions, that consistent estimation of all the required moments is possible from uniformly scalar quantized data regardless of the quantization coarseness. This consistent estimation requires the solution of nonlinear equations. Very simple approximations that avoid these nonlinear equations are used to develop a practical adaptive coding technique. Promising experimental results obtained with this method are presented.

关键词： Transform coding Quantization Decoding Nonlinear equations Statistics Costs Computer science State estimation adaptive coding Huffman coding

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Group 3 error-free facsimile terminal for analog cellular networks

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IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY 1996年第1期45卷 64-73页

作者： Kawabe, M Kato, T Sato, T Bessho, M Fukasawa, A Communication Systems Laboratory Oki Electric Industry Company Limited Tokyo Japan

Group 3 error-free facsimile terminal for use in an analog cellular network has been developed, This facsimile terminal is provided with the International Telecommunication Union (ITU-T, formerly CCITT) T.30 recommendation protocol and an adaptive error control scheme (AECS) for Group 3 communication and error-free communication, The AECS monitors the channel conditions and selects the optimum error correction code, ITU-T V.27ter is used as the modulation method and the transmission rate is 4800 bps, This system is compatible with the modified Huffman (MH), modified READ (MR), and modified modified READ (MMR) image data compression codes. The average communication time of this facsimile terminal is 40 s per page under moving condition through the analog cellular network.

关键词： adaptive codes cellular radio error correction codes facsimile facsimile equipment modulation protocols radio networks telecommunication standards 40 s 4800 bit/s CCITT Group 3 communication Group 3 error-free facsimile terminal ITU-T ITU-T V.27ter Inter TELEPHOTOGRAPHY(FACSIMILE) modulation mode Error-free operations Error correction codes adaptive coding cellular radio telecommunication standards protocols Radio networks

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Learning to compress ergodic sources

Learning to compress ergodic sources

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Data Compression Conference (DCC)

作者： J. Baxter J. Shawe-Taylor Department of Computer Science Royal Holloway University of London Surrey UK

Abstract only given. We present an adaptive coding technique which is shown to achieve optimal coding in the limit as the size of the text grows, while the data structures associated with the code only grow linearly with the text. The approach relies on Huffman codes which are generated relative to the context in which a particular character occurs. The Huffman codes themselves are inferred from the data that has already been seen. A key part of the paper involves showing that the loss per character incurred by the learning process tends to zero as the size of the text tends to infinity. This involves an analysis in an on-line learning framework bounding the cumulative loss, where loss is defined to be the excess code length. By using the Bayes prediction distribution and code the expected loss per character converges to zero at the best possible rate of O(log n/n). By allowing the length of contexts to grow in response to commonly occurring subsequences, the coding is efficient precisely where it needs to be, hence achieving a high compression rate at a relatively low overhead in terms of data structure storage.

关键词： Computer science Data structures adaptive coding Character generation H infinity control Mathematics Economic forecasting

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Wavelets and human visual perception in image compression

Wavelets and human visual perception in image compression

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International Conference on Pattern Recognition

作者： M.G. Albanesi University of Pavia Pavia Italy

The paper describes a new adaptive coding technique for still, grey-level images. The algorithm is based on a multi-resolution decomposition on biorthogonal wavelet basis and it includes different nonlinear models of the human visual perception in the compression task. Quantization is adaptive, and it is based on considerations about the contrast experiments which aim at determining in which conditions (contrast of the input image, compression ratio) the inclusion of the models improves the performance. The results are compared with standard techniques which do not include considerations about human visual perception.

关键词： Humans Visual perception Image coding Image reconstruction Transfer functions Visual system Multimedia databases Linear systems adaptive coding Quantization

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Channel-matched hierarchical table-lookup vector quantization for transmission of video over wireless channels

Channel-matched hierarchical table-lookup vector quantizatio...

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IEEE International Conference on Image Processing

作者： H. Jafarkhani N. Farvardin Dept. of Electr. Eng. Maryland Univ. College Park MD USA Department of Electrical Engineering and Institute for Systems Research University of Maryland College Park MD USA

We propose a channel-matched hierarchical table-lookup vector quantizer (CM-HTVQ) which provides some robustness against the channel noise. We use a finite-state channel to model slowly fading channels and propose an adaptive coding scheme to transmit a source over wireless channels. The performance of CM-HTVQ is in general slightly inferior to that of channel-optimized vector quantizer (COVQ) (the performances coincide at some cases); however, the encoder complexity of CM-HTVQ is much less than the encoder complexity of COVQ.

关键词： Vector quantization Decoding Noise robustness Fading Speech coding Discrete wavelet transforms Educational institutions adaptive coding Source coding Image coding

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Improving the performance of Federal Standard 1016 (CELP)

Improving the performance of Federal Standard 1016 (CELP)

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IEEE Southeastcon

作者： K. Rutherford S. McClellan R. Adhami SRT Electro Optics Inc. Birmingham AL USA Electrical & Computer Engr University of Alabama Birmingham USA Electrical Engr University of Alabama-Huntsville USA

We modify the Fed. Std. 1016 speech compression algorithm to include lag-indexed VQ of the pitch filter parameters. Using side by side paired comparison tests and untrained listeners, we compare the subjective perform... 详细信息

关键词： Delay Books Speech adaptive coding Filters Linear predictive coding Computational complexity Noise reduction 1f noise Compression algorithms

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Channel adaptive coding techniques through application of higher order moments

Channel adaptive coding techniques through application of hi...

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IEEE International Symposium on Information Theory

作者： W.A. Clarke L. Fouche A.S.J. Helberg H.C. Ferreira Laboratory for Cybernetics Rand Afrikaans University Auckland Park South Africa Laboratory for Cybernetics Rand Afrikaans University South Africa

We investigate the use of higher order code word moments to shape the power spectral density of codes. Several codes are presented that combine different spectral shaping techniques. The insertion/deletion and additive error correcting capabilities of these codes are investigated and simple decoding procedures are presented. Finally, we give an example for the use of a higher order spectral zero code.< >

关键词： adaptive coding Error correction codes Frequency Bandwidth Laboratories Cybernetics Africa Decoding Block codes Speech coding

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adaptive MHDCT coding of images

Adaptive MHDCT coding of images

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IEEE International Conference on Image Processing

作者： M. Barazande-Pour J.W. Mark Department of Electrical and Computer Engineering University of Waterloo Waterloo ONT Canada

An adaptive coding scheme, based on a modification of the discrete cosine transformation, is used to encode image signals. The coding performance is compared with those of the DCT and the Walsh-Hadamard transform. The proposed coding scheme is simpler than the DCT, but its performance is quite close to that of the DCT. The adaptivity in our coder is achieved by using a suitable classification method and distributing the available channel capacity to different classes according to their energy level.< >

关键词： Image coding Discrete cosine transforms Bit rate Discrete transforms adaptive coding Channel capacity Energy states Data compression Fourier transforms Karhunen-Loeve transforms

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SOURCE-coding BY CLASSIFICATION - 91-715

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IEEE TRANSACTIONS ON COMMUNICATIONS 1995年第11期43卷 2821-2832页

作者： VOGEL, P PHILIPS KOMMUN IND AG W-8500 NURNBERGGERMANY

adaptive source coding is investigated which is performed by a blockwise classification of the source symbols and selection of a coder depending on the class. As justification for adaptive coding, an upper bound is used for the rate distortion function of a stationary source depending on blockwise classification. The main result of the paper states that classification is appropriate to exploit statistical dependencies other than correlation. Such statistical dependencies are described for the prediction error of a coding scheme for moving pictures at 64 kbit/s and are exploited for upper bounding the rate distortion function of the prediction error and improving the coding scheme.

关键词： Source coding Resource description framework Rate-distortion Upper bound Switches Quantization Image reconstruction adaptive coding Speech coding Image communication

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