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IEEE International Symposium on Circuits and Systems (ISCAS)

作者： C.-T. See K.-T. Lo W.-K. Cham Dept. of Electron. Eng. Chinese Univ. of Hong Kong Shatin Hong Kong Department of Electronic Engineering Chinese University of Hong Kong Hong Kong China

A minimum edge difference (MED) predictor is proposed to enhance the performance of the basic JPEG (Joint Photographic Experts Group) system. The MED predictor uses the edge difference between adjacent blocks for prediction of the DC coefficient of the current block. Analysis based on a statistical model shows that the proposed predictor can encode the DC coefficients more effectively than the JPEG predictor and the optimal single element 1-D predictor. Computer simulation using real images also shows that, when the proposed MED predictor is used, there is about 5% bit rate reduction over the basic JPEG system.< >

关键词： Image coding transform coding Image storage Predictive models Pulse modulation ISO standards Discrete cosine transforms Huffman coding Computer simulation Bit rate

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Constrained-storage vector quantization in high fidelity audio transform coding

Constrained-storage vector quantization in high fidelity aud...

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International Conference on Acoustics, Speech, and Signal Processing (ICASSP)

作者： W.-Y. Chan A. Gersho Center of Information Processing Research Department of Electrical & Computer Engineering University of California Santa Barbara CA USA

The concept and design methods for efficient use of vector quantization (VQ) in high-fidelity audio coding are presented. It is demonstrated that with constrained-storage VQ (CSVQ), tree-structured codebooks can be constructed for very high rates without incurring an exponential growth in storage complexity and without impairing the rate-distortion performance. Nonlinear interpolative VQ allows efficient coding of the power envelope needed for transform-coefficient normalization and adaptive distortion assignment. These techniques lead to a substantial reduction in the overall bit rate and codebook storage for the audio coder.< >

关键词： Vector quantization transform coding Nonlinear distortion Discrete cosine transforms Rate-distortion Product codes Bit rate Performance gain Design methodology Audio coding

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Texture analysis based on affine transform coding

Texture analysis based on affine transform coding

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IEEE International Conference on Image Processing

作者： Jih-Ming Feng Taoi Hsu Jiann-Ling Kuo Chung Cheng Institute of Technology China

A novel very-low-bit-rate textured image compression scheme is proposed in this scheme, both texture self-similarity property and affine transform are used as basis to achieve coding tasks. An input texture image can be reconstructed from both the prototype block spectral and the corresponding affine transform parameters. These parameters are estimated from the prototype block spectral and that of the rest blocks using the multiresolution Fourier transform, MFT, of the input image. In the synthesizing process, two different groups of parameters are generated, the MFT coefficients of the prototype block and the estimated affine parameters amongst blocks. In order to achieve the very-low-bit-rate coding scheme, this paper presents the quantization and coding scheme of the transformed coefficients and the estimated affine parameters. Consequently, figures of the compression and distortion ratio of the reconstructed image can be measured to analyze the structure of textured image over various scales.

关键词： transform coding Image coding Prototypes Parameter estimation Image texture analysis Image reconstruction Image resolution Fourier transforms Quantization Distortion measurement

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Edge compensated transform coding

Edge compensated transform coding

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IEEE International Conference on Image Processing

作者： W.E. Lynch A.R. Reibman B. Liu ECE Department Concordia University Montreal QUE Canada AT and T Bell Laboratories Inc. Holmdel NJ USA EE Department Princeton University Princeton NJ USA

transform based image compression has difficulty with image regions containing edges. Edge compensated transform coding (ECTC) addresses this problem by preprocessing to remove edges. This preprocessing is adapted to transform coding. The edge information is sent in a side channel and the edges are replaced at the receiver. Subjective improvement is demonstrated.< >

关键词： transform coding Image coding Image edge detection Laplace equations Image reconstruction Compaction Frequency Image segmentation Radio access networks Image generation

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Error Correction Block coding Can Combine With Adaptive transform coding To Allow Coherent Speech Transmission Over Channels With Bit Error Rates of 1 in 100

Error Correction Block Coding Can Combine With Adaptive Tran...

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Southern African Conference on Communications and Signal Processing (COMSIG)

作者： D. Mashao R.M. Braun Department of Electrical and Electronic Engineering University of Cape Town Rondebosch South Africa

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BLOCK transform IMAGE-coding BY MULTISTAGE VECTOR QUANTIZATION WITH OPTIMAL BIT ALLOCATION

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IEEE TRANSACTIONS ON COMMUNICATIONS 1991年第9期39卷 1360-1369页

作者： WANG, LM GOLDBERG, M Microtel Pacific Res. Ltd. Burnaby BC Canada Department of Electrical Engineering University of Ottawa Ottawa ONT Canada

In this paper, we introduce a multistage vector quantization technique (MVQ-OBA) applied to the transform coefficients where the effective number of bits assigned to each coefficient is proportional to the coefficient variance. A (scalar) optimal bit allocation map for a given bit rate, {B(ij)}, is first found based on the variances of the transform coefficients. The optimal bit allocation map {B(ij)} is then sliced into a set of bit allocation planes {B(k, ij), k = 0, 1, ...} by applying a set of thresholds {T(k), k = 0, 1, ...} Here, B(k, ij) indicates the number of bits assigned to coefficient (i, j) at stage k. The transformed image is then vector quantized on a stage-by-stage basis where, at each stage k, only the (residual error) coefficients assigned a nonzero number of bits are combined into vectors and vector quantized with a codebook of size 2-SIGMA-i, j (B)k, ij. Since only part of the coefficients are included into vectors and a relatively small codebook is used at each stage, both the overhead for transmitting the codebook and the complexity in codebook design are significantly reduced. Furthermore, as MVQ-OBA operates in a multistage manner where the information transmitted up to each stage corresponds to an approximation of the image, it is well suited for progressive image transmission. Finally, MVQ-OBA is shown to be competitive with other transform coding techniques in terms of performance.

关键词： transform coding multistage vector quantization progressive transmission block transform codebook Simulation results

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Wyner-Ziv quantization and transform coding of noisy sources at high rates

Wyner-Ziv quantization and transform coding of noisy sources...

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Asilomar Conference on Signals, Systems & Computers

作者： D. Rebollo-Monedero S. Rane B. Girod Information Systems Laboratory Department of Electrical Eng. University of Stanford Stanford CA USA

We extend Wyner-Ziv high-rate quantization and transform coding theory to the case in which a noisy observation of some source data is available at the encoder, but we are interested in estimating the unseen source data at the decoder, with the help of side information. Ideal Slepian-Wolf coders are assumed, thus rates are conditional entropies of quantization indices given the side information. transform coders of noisy images for different communication constraints are compared. Experimental results show that the Wyner-Ziv transform coder achieves a performance close to the case in which the side information is also available at the encoder.

关键词： Quantization transform coding Decoding Remote sensing Noise reduction Source coding Information systems Entropy Image sensors Rate-distortion

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An edge-based splitting criterion for adaptive transform coding

An edge-based splitting criterion for adaptive transform cod...

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1993 IEEE International Conference on Acoustics, Speech, and Signal Processing

作者： F.G.B. De Natale G.S. Desoli S. Fioravanti D.D. Giusto Department of Biophysical and Electronic Engineering University of Genoa Genoa Italy

A novel splitting strategy for variable block-size image coding based on edge information is presented, which makes it possible to reduce the number of blocks to be encoded while maintaining an in-depth split in edge areas. This approach has been applied to a standard transform coding algorithm, and results have been compared with those obtained by a classical splitting structure. Tests showed a notable increase in the compression factor under the same SNR conditions. Reconstructed images are affected by the blocking effect to a smaller extent, as the problem of generating a large number of small blocks in the uniform areas surrounding an edge is overcome by the proposed split topology.< >

关键词： transform coding Image coding Discrete cosine transforms Quantization Approximation error Frequency estimation Maintenance engineering Testing Image reconstruction Topology

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Nonlinear transform coding for VVC Intra coding

Nonlinear Transform Coding for VVC Intra Coding

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Picture coding Symposium, PCS

作者： Michael Schäfer Jonathan Pfaff Heiko Schwarz Detlev Marpe Thomas Wiegand Fraunhofer Institute for Telecommunications - Heinrich Hertz Institute Berlin Germany Institute of Computer Science Free University of Berlin Germany Department of Telecommunication Systems Technical University of Berlin Germany

ISBN: (数字)9798350358483

ISBN: (纸本)9798350358490

Modern hybrid video codecs like Versatile Video coding (VVC) heavily rely on transform coding tools. Given a prediction signal at the encoder, the residual is transformed using trigonometric transforms. Rate-distortion-optimized quantization (RDOQ) and entropy coding of the transformed residual is well-understood due to the orthogonality and the energy compaction of these transforms. Within this setting, there is considerable success in optimizing secondary orthogonal transforms. The most prominent example is the Low-Frequency Non-Separable transform (LFNST) in VVC. However, training nonlinear transforms without re-designing the RDOQ and entropy coding stage is a hard problem. In learned image compression, variational autoencoders have shown impressive results, but they use their own entropy model, remain difficult to train for small blocks and RDOQ is nontrivial for them. This paper describes a novel design of a nonlinear transform network for block-based video coding. Given a transform block, a fully-connected neural network predict coefficients from previously reconstructed ones and the adherent block boundary, such that only the residual coefficients need to be transmitted. Furthermore, another neural network filters the entire transform block before the inverse transform is applied and the intra prediction signal is added. Against the Versatile Video coding Test Model 14.2 (VTM-14.2), luma bit-rate savings of approximately 1.9 % are reported for the All-Intra configuration.

关键词： Video coding Image coding Laplace equations Filters Neural networks Bit rate transform coding

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Adapting transform coding to texturally segmented images

Adapting transform coding to texturally segmented images

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Asilomar Conference on Signals, Systems & Computers

作者： S. Sanei R.I. Kitney R. Benjamin Electrical Engineering Department Abadan Institute of Technology Ahvaz Iran Biomedical Systems Group Electrical Engineering Department Imperial College London London UK

Nonstationarity in image textures requires implementation of variable-size partitioning into stationary regions for coding purposes. The popular methods in regular decomposition fail in accurately following the various region boundaries. In the present work, the boundaries of different textures in the image are detected using a one-dimensional model of each row of the image. The autoregressive algorithm operates in 8 directions to enable an efficient detection of the boundaries. The edge map is then achieved by taking the result of edge detection operation in all directions into account. transform coding and run-length coding are applied to encode the textures and the boundaries, respectively.< >

关键词： transform coding Image segmentation Image coding Image edge detection Image storage Shape Educational institutions Image texture Partitioning algorithms Encoding

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