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Variable length integer codes based on radix number system conversion

ELECTRONICS LETTERS 2016年第16期52卷 1385-1386页

作者： Joseph, Nelson Raja Planichamy, Jaganathan Sandanam, Domnic Bharathiyar Univ R&D Ctr Coimbatore Tamil Nadu India PSNA Coll Engn & Technol Dindigul India Natl Inst Technol Tiruchirappalli India

A new coding scheme called radix conversion variable length code (RCVLC) is proposed to represent non-negative integers from small values to very large values. RCVLC obtains lowest code length to represent mid-range and large-range integers than Fibonacci code, Elias codes and other existing schemes. This RCVLC is applied as an entropy coder of the Burrows Wheeler Transform data compressor to compress Calgary corpus which contains both binary and text files. It is observed from the experimental results that the new RCVLC obtains better compression than the existing coding schemes on an average.

关键词： data compression digital arithmetic entropy codes variable length codes Burrows-Wheeler transform data compressor Calgary corpus compression Elias codes Fibonacci code RCVLC entropy coder nonnegative integers radix conversion variable length code radix number system conversion text files variable length integer codes

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Highly Efficient Compression Algorithms for Multichannel EEG

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IEEE TRANSACTIONS ON NEURAL SYSTEMS AND REHABILITATION ENGINEERING 2018年第5期26卷 957-968页

作者： Shaw, Laxmi Rahman, Daleef Routray, Aurobinda IIT Kharagpur Dept Elect Engn Kharagpur 721302 W Bengal India

The difficulty associated with processing and understanding the high dimensionality of electroencephalogram (EEG) data requires developing efficient and robust compression algorithms. In this paper, different lossless compression techniques of single and multichannel EEG data, including Huffman coding, arithmetic coding, Markov predictor, linear predictor, context-based error modeling, multivariate autoregression (MVAR), and a low complexity bivariate model have been examined and their performances have been compared. Furthermore, a high compression algorithm named general MVAR and a modified context-based error modeling for multichannel EEG have been proposed. The resulting compression algorithm produces a higher relative compression ratio of 70.64% on average compared with the existing methods, and in some cases, it goes up to 83.06%. The proposed methods are designed to compress a large amount of multichannel EEG data efficiently so that the data storage and transmission bandwidth can be effectively used. These methods have been validated using several experimental multichannel EEG recordings of different subjects and publicly available standard databases. The satisfactory parametric measures of these methods, namely percent-root-mean square distortion, peak signal-to-noise ratio, root-mean-square error, and cross correlation, show their superiority over the state-of-the-art compression methods.

关键词： Losslesscompression EEG linear prediction context-based entropy coder MVAR

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Large-Alphabet Semi-Static entropy Coding Via Asymmetric Numeral Systems

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ACM TRANSACTIONS ON INFORMATION SYSTEMS 2020年第4期38卷 1-33页

作者： Moffat, Alistair Petri, Matthias Univ Melbourne Sch Comp & Informat Syst Melbourne Vic 3010 Australia

An entropy coder takes as input a sequence of symbol identifiers over some specified alphabet and represents that sequence as a bitstring using as few bits as possible, typically assuming that the elements of the sequence are independent of each other. Previous entropy coding methods include the well-known Huffman and arithmetic approaches. Here we examine the newer asymmetric numeral systems (ANS) technique for entropy coding and develop mechanisms that allow it to be efficiently used when the size of the source alphabet is large-thousands or millions of symbols. In particular, we examine different ways in which probability distributions over large alphabets can be approximated and in doing so infer techniques that allow the ANS mechanism to be extended to support large-alphabet entropy coding. As well as providing a full description of ANS, we also present detailed experiments using several different types of input, including data streams arising as typical output from the modeling stages of text compression software, and compare the proposed ANS variants with Huffman and arithmetic coding baselines, measuring both compression effectiveness and also encoding and decoding throughput. We demonstrate that in applications in which semi-static compression is appropriate, ANS-based coders can provide an excellent balance between compression effectiveness and speed, even when the alphabet is large.

关键词： Asymmetric numeral systems compression Burrows-Wheeler transform entropy coder Huffman code arithmetic code

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Complete Focal Plane Compression Based on CMOS Image Sensor Using Predictive Coding

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Transactions of Tianjin University 2015年第1期21卷 83-89页

作者：姚素英于潇高静徐江涛 School of Electronics and Information Engineering Tianjin University

In this paper, a CMOS image sensor(CIS) is proposed, which can accomplish both decorrelation and entropy coding of image compression directly on the focal plane. The design is based on predictive coding for image decorrelation. The predictions are performed in analog domain by 2×2 pixel units. Both the prediction residuals and original pixel values are quantized and encoded in parallel. Since the residuals have a peak distribution around zero,the output codewords can be replaced by the valid part of the residuals' binary mode. The compressed bit stream is accessible directly at the output of CIS without extra disposition. Simulation results show that the proposed approach achieves a compression rate of 2. 2 and PSNR of 51 on different test images.

关键词： CMOS image sensor focal plane compression predictive coding entropy coder

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Recursive architecture using pipeline stall for low complexity MPEG-4 ALS encoder

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ELECTRONICS LETTERS 2011年第9期47卷 567-569页

作者： Kim, D-S Kim, B-S Lee, S-S Choi, B-H KETI Multimedia IP Res Ctr Songnam South Korea

An MPEG-4 audio lossless coding (ALS) encoder consists of a short-term predictor, a joint coder, a long-term predictor, and an entropy coder for audio signal compression. Especially, the short-term predictor is the highest complexity in MPEG-4 ALS encoder implementation because linear prediction coefficients (LPCs) for the short-term predictor are obtained from the Levinson-Durbin recursion algorithm that uses correlations of the input signals. LPCs are used for the finite impulse response (FIR) filter of the short-term predictor and its maximum coefficient order is up to 1023. Proposed is an area-efficient short-term predictor through the recursive architecture using pipeline stall and the modified radix-2 FIR algorithm is proposed. The proposed shot-term predictor has a reduction of complexity by about 95% compared to the radix-2 1024 tap FIR filter.

关键词： modified radix-2 FIR algorithm pipeline stall data compression finite impulse response filter entropy codes Levinson-Durbin recursion algorithm audio coding entropy coder FIR filter FIR filters recursive architecture audio signal compression long-term predictor area-efficient short-term predictor Filtering methods in signal processing linear prediction coefficients joint coder Speech and audio coding low complexity MPEG-4 ALS encoder MPEG-4 audio lossless coding

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ANS-Based Index Compression 17

ANS-Based Index Compression

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ACM Conference on Information and Knowledge Management (CIKM)

作者： Moffat, Alistair Petri, Matthias Univ Melbourne Melbourne Vic Australia

ISBN: (纸本)9781450349185

Techniques for effectively representing the postings lists associated with inverted indexes have been studied for many years. Here we combine the recently developed "asymmetric numeral systems" (ANS) approach to entropy coding and a range of previous index compression methods, including VByte, Simple, and Packed. The ANS mechanism allows each of them to provide markedly improved compression effectiveness, at the cost of slower decoding rates. Using the 426 GiB Gov2 collection, we show that the combination of blocking and ANS-based entropy-coding against a set of 16 magnitude based probability models yields compression effectiveness superior to most previous mechanisms, while still providing reasonable decoding speed.

关键词： postings list asymmetric numeral systems entropy coder index compression inverted index

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Index Compression Using Byte-Aligned ANS Coding and Two-Dimensional Contexts 18

Index Compression Using Byte-Aligned ANS Coding and Two-Dime...

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11th ACM International Conference on Web Search and Data Mining

作者： Moffat, Alistair Petri, Matthias Univ Melbourne Melbourne Vic Australia

ISBN: (纸本)9781450355810

We examine approaches used for block-based inverted index compression, such as the OptPFOR mechanism, in which fixed-length blocks of postings data are compressed independently of each other. Building on previous work in which asymmetric numeral systems (ANS) entropy coding is used to represent each block, we explore a number of enhancements: (i) the use of two-dimensional conditioning contexts, with two aggregate parameters used in each block to categorize the distribution of symbol values that underlies the ANS approach, rather than just one;(ii) the use of a byte-friendly strategic mapping from symbols to ANS codeword buckets;and (iii) the use of a context merging process to combine similar probability distributions. Collectively, these improvements yield superior compression for index data, outperforming the reference point set by the Interp mechanism, and hence representing a significant step forward. We describe experiments using the 426 GiB gov2 collection and a new large collection of publicly-available news articles to demonstrate that claim, and provide query evaluation throughput rates compared to other block-based mechanisms.

关键词： Index compression inverted index postings list entropy coder asymmetric numeral systems

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Using neighbouring nodes for the compression of octrees representing the geometry of point clouds 19

Using neighbouring nodes for the compression of octrees repr...

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10th ACM Multimedia Systems Conference (ACM MMSys)

作者： Lasserre, Sebastien Flynn, David Qu, Shouxing BlackBerry Courbevoie France BlackBerry Dusseldorf Germany BlackBerry Ottawa ON Canada

ISBN: (纸本)9781450362979

The geometry of a point cloud is commonly represented by an octree recursively decomposing a 3D volume into eight child sub-volumes. Said volumes and sub-volumes are associated with nodes and child-nodes of the octree. The geometry is defined by the occupancy information indicating the presence or not of a point in each of the sub-volumes. This naturally leads to an eight-bit occupancy information to be coded for each internal node of the tree. This paper introduces a new binarization scheme to efficiently compress the occupancy information using an optimal set of binary entropy coders. Then, it is shown how using the occupancy information of neighbouring nodes helps to compress the occupancy bits associated with the child nodes of the current node. This information is used to contextualise the binarization scheme by computing, firstly a neighbour configuration, secondly a number of neighbours with occupied child nodes adjacent to the current child node, and thirdly an intra predictor. Objective results show lossless geometry compression gains between 60% and 75% on virtual reality oriented dense point clouds used by MPEG, reaching sub-bit per point bit-rates for the lossless intra coding of such point clouds. Solid gains (between 5% and 25% depending upon the sampling) are also observed on sparse point clouds captured by a LiDAR (Light Detection and Ranging) device attached to a moving vehicle or representing 3D maps.

关键词： Point Cloud Compression Octree Occupancy Information entropy coder Prediction Neighbouring Nodes

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Advantages of uniform scalar dead-zone quantization in image coding system

Advantages of uniform scalar dead-zone quantization in image...

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International Conference on Communications, Circuits and Systems

作者： Ya, JH Yunnan Univ Coll Elect Engn Kunming 650091 Peoples R China

ISBN: (纸本)0780386477

Quantization is an element of lossy image compression system. In this paper, we introduce three basic quantization methods commonly used in JPEG or JPEG-2000 standard, USQ(uniform scalar quantization), USDZQ(uniform scalar dead-zone quantization) and UTCQ(universal trellis coded quantization) which is recently regarded as a competitive quantization strategy. We apply these three types of quantizers to the DWT transformed coefficients of images. The performance comparisons show that the UTCQ can quantize data more precisely than the two other quantizers with the same step size. But when they are combined with the zero or high order entropy coders, the USDZQ is the best instead. In these comparisons, we show that if the dead-zone is designed carefully, the USDZQ can effectively reduce the output bits of the entropy coder, although it reduces quantization precision by discarding some data around zero. These results show that the threshold we choose for the USDZQ is reasonable, it is suitable for transform based image compression system.

关键词： uniform scalar quantization(USQ) uniform scalar dead-zone quantization(USDZQ) universal trellis coded quantization(UTCQ) entropy coder

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A memory-saving system including DWT and EC for jpeg2000 implementation

A memory-saving system including DWT and EC for jpeg2000 imp...

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IEEE International Conference on Image Processing (ICIP 2006)

作者： Xu, Chao Han, Yan-Ju Hu, Su-Fang Peking Univ Natl Lab Machine Percept Beijing 100871 Peoples R China

ISBN: (纸本)9781424404810

In this paper, a new system including Discrete Wavelet Transform (DWT) and entropy coder (EC) is presented for JPEG2000 implementation. The system accomplishes a seamless connection between DWT and EC. To reach the goal, an EC-based DWT scheme is proposed, and a new EC architecture is designed that encodes three code-blocks concurrently. The system reduces the memory requirement significantly. Compared to the QCB-DWT scheme, more than 72 percent of memory is removed. And it is a high speed encoding system, able to encode 720x576 video more than 40 frames per second at 54MHz clock frequency.

关键词： JPEG2000 DWT entropy coder

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