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Representing Visual Objects in HEVC coding Loop

IEEE JOURNAL ON EMERGING AND SELECTED TOPICS IN CIRCUITS AND SYSTEMS 2014年第1期4卷 5-16页

作者： Huang, Tiejun Dong, Siwei Tian, Yonghong Peking Univ Sch Elect Engn & Comp Sci Natl Engn Lab Video Technol Beijing 100871 Peoples R China

Different from the previous video coding standards that employ fixed-size coding blocks (and macroblocks), the latest high efficiency video coding (HEVC) introduces a quadtree structure to represent variable-size coding blocks in the coding loop. The main objective of this study is to investigate a novel way to reuse these variable-size blocks to represent the foreground objects in the picture. Towards this end, this paper proposes three methods, i.e., flagging the blocks lying in the object regions flagging compression blocks (FCB), adding an object tree in each coding Tree Unit to describe the objects' shape in it additional object tree (AOT) and confining the block splitting procedure to fit the object shape confining by shape (CBS). Among them, FCB and CBS add a flag bit in the syntax description of the block to indicate whether it lies in the objects region, while AOT adds a separate quadtree to represent the objects. For all these methods, the additional bits are then fed into the HEVC entropy coding module to compress. As such, the representation of visual objects in the pictures can be implemented in the HEVC coding loop by reusing the variable-size blocks and entropy coding, without additional coding tools. The experiments on six manually-segmented HEVC testing sequences (three in 1080P and three in 720P) demonstrate the feasibility and effectiveness of our proposal. To represent the objects in the 1080P testing sequences, the BD rate increases of FCB, AOT, and CBS over the HEVC anchor are 1.57%, 3.27%, and 5.93% respectively;while for the 720P conference videos, those are 4.57%, 17.23%, and 26.93% (note that the average bitrate of the anchor is only 1009 kb/s).

关键词： entropy coding high efficiency video coding (HEVC) variable-size coding blocks video coding visual object representation

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SUBBAND HDTV coding USING HIGH-ORDER CONDITIONAL STATISTICS

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IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS 1993年第1期11卷 65-76页

作者： LEI, SM CHEN, TC TZOU, KH COMSAT LABS CLARKSBURGMD 20871

This paper presents an HDTV coding scheme which is capable of achieving high quality below 20 Mb/s. The system employs motion estimation/compensation followed by four-band subband splitting. The band signals are then subject to quantization and coded by an innovative high-order entropy coder. It is shown that this high-order entropy coder generates a bit rate nearly 30% lower than the popular run-length/Huffman coding for motion-compensated frame differences. Also, about 15% improvement is observed for the intrafield coded data. In order to reduce the complexity of the high-order entropy coder for high-speed implementation, two techniques, codebook reduction and nonuniform quantization of conditioning samples, are developed. Furthermore, a method of selecting conditioning samples and their order, based on mutual information between samples, is proposed. This method is shown to outperform several other systematic and intuitive approaches. Based on our simulations, the new system at about 20 Mb/s is shown to achieve picture quality comparable to the 120 Mb/s six-band intrafield coding system which we investigated before.

关键词： HDTV Statistics B-ISDN entropy coding Bit rate Motion estimation Mutual information Optical fiber LAN Local area networks Quantization

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GENERATION INTERVAL DISTRIBUTION CHARACTERISTICS OF PACKETIZED VARIABLE-RATE VIDEO coding DATA STREAMS IN AN ATM NETWORK

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IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS 1989年第5期7卷 833-841页

作者： KISHIMOTO, R OGATA, Y INUMARU, F NTT Transmission Systems Laboratories Yokosuka Kanagawa Japan NTT Transmission Syst. Lab. Kanagawa Japan

A description is given of the packetized data stream characteristics of variable-rate video coding in an asynchronous transfer mode (ATM) network. Variable-rate video coding characteristics are presented using motion-compensated adaptive intra-interframe prediction and entropy coding. The peak/mean entropy ratio, i.e., the burstiness of the TV conference video signals, ranges from 3 to 4. A method is proposed to transmit the packets of the three outputs of the variable-rate video coder: prediction errors, motion vector information, and quantizer selection information. The packet generation interval distribution characteristics of the prediction errors and motion vector information are clarified. It is shown that the generation interval distribution of prediction errors and motion vector information are not characterized by a simple Erland distribution, but by a combination of different distributions.< >

关键词： Character generation Video coding Asynchronous transfer mode Streaming media Bit rate Videoconference TV entropy coding Layout Communication networks

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Successive refinement lattice vector quantization

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IEEE TRANSACTIONS ON IMAGE PROCESSING 2002年第12期11卷 1337-1348页

作者： Mukherjee, D Mitra, SK Univ Calif Santa Barbara Image Proc Lab Dept Elect & Comp Engn Santa Barbara CA 93106 USA

Lattice Vector Quantization (LVQ) solves the complexity problem of LBG based vector quantizers, yielding very general codebooks. However, a single stage LVQ, when applied to high resolution quantization of a vector, may result in very large and unwieldy indices, making it unsuitable for applications requiring successive refinement. The goal of this work is to develop a unified framework for progressive uniform quantization of vectors without having to sacrifice the mean- squared-error advantage of lattice quantization. A successive refinement uniform vector quantization methodology is developed, where the codebooks in successive stages are all lattice codebooks, each in the shape of the Voronoi regions of the lattice at the previous stage. Such Voronoi shaped geometric lattice codebooks are named Voronoi lattice VQs (VLVQ). Measures of efficiency of successive refinement are developed based on the entropy of the indices transmitted by the VLVQs. Additionally, a constructive method for asymptotically optimal uniform quantization is developed using tree-structured subset VLVQs in conjunction with entropy coding. The methodology developed here essentially yields the optimal vector counterpart of scalar "bitplane-wise" refinement. Unfortunately it is not as trivial to implement as in the scalar case. Furthermore, the benefits of asymptotic optimality in tree-structured subset VLVQs remain elusive in practical nonasymptotic situations. Nevertheless, because scalar bitplane- wise refinement is extensively used in modern wavelet image coders, we have applied the VLVQ techniques to successively refine vectors of wavelet coefficients in the vector set-partitioning (VSPIHT) framework. The results are compared against SPHIT and the previous Successive Approximation Wavelet Vector Quantization (SA-W-VQ) results of Sampson, da Silva, and Ghanbari.

关键词： entropy coding lattice vector quantization vector SPIHT Voronoi region wavelets zerotree

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Multisymbol Architecture of the entropy Coder for H.265/HEVC Video Encoders

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IEEE TRANSACTIONS ON VERY LARGE SCALE INTEGRATION (VLSI) SYSTEMS 2020年第12期28卷 2573-2583页

作者： Pastuszak, Grzegorz Warsaw Univ Technol Inst Radioelect & Multimedia Technol PL-00661 Warsaw Poland

In video compression, throughputs of entropy encoders based on arithmetic coding are limited. This article presents the architecture of the entropy coder able to process in each clock cycle much more binary symbols than previous works. The architecture takes advantage of the multisymbol implementation of the binary arithmetic coder (BAC) developed earlier. To balance high throughputs of the BAC, fast implementations of binarization, context modeling, and probability model (PM) update are developed. The main improvement in the symbol rate stems from the decomposition of the processing path into many parallel ones. Critical paths associated with state transitions are shortened since each path updates the PM only for one context selected in each clock cycle. The negative impact on the symbol rate is compensated by the context-based symbol reordering. Although paths have variable bin/symbol rates, the applied buffering strategy improves the continuity of two data streams directed to the BAC, separately for context-coded and bypass-mode symbols. The entropy coder synthesized for the 90-nm TSMC technology consumes 273-k gates and operates at 570 MHz. It achieves the average symbol rate of 13.08 bins per clock cycle and the throughput of 7455 Mbins/s for high-quality H.265/HEVC compression.

关键词： entropy Throughput Clocks Streaming media Encoding Context modeling Multiplexing Binary arithmetic coding entropy coding field-programmable gate array (FPGA) H265 HEVC UHDTV video compression

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Analysis of Compressing PAPR-Reduced OFDM IQ Samples for Cloud Radio Access Network

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IEEE TRANSACTIONS ON BROADCASTING 2022年第3期68卷 765-779页

作者： Shehata, Aya Mary, Philippe Crussiere, Matthieu Univ Rennes INSA Rennes CNRS IETR UMR 6164 F-35000 Rennes France

A common problem of the virtualized cloud radio access network architecture (C-RAN) is the compression of the time-domain IQ samples before transmission over the fronthaul link. Considering a multicarrier waveform such as OFDM, whose IQ samples follow a quasi-Gaussian distribution, the conventional Gaussian quantizer may be used as the optimal solution to the compression problem. However, since the high peak-to-average power ratio (PAPR) of OFDM signals remains a serious problem, various techniques may be employed to reduce the time-domain fluctuations of the IQ samples in the OFDM, resulting in a change in its distribution. The latter fact makes the Gaussian quantizer suboptimal. The literature lacks a performance analysis of the conventional OFDM-based compression techniques when the PAPR of the OFDM signal is reduced. Therefore, in this paper, we study for the first time the impact of reducing the PAPR of the OFDM signal before compression in the C-RAN architecture through rate-distortion analysis. We consider clipping and tone reservation PAPR reduction algorithms. The former is the simplest PAPR reduction approach, while the latter is one of the most effective algorithms used in broadcasting standards such as DVB-T2 and ATSC 3.0. We first derive the distribution of the PAPR-reduced OFDM IQ samples. This is used to optimize the thresholds and codebook levels of a non-uniform scalar quantizer and the number of quantization bits allocated for each quantized level in the entropy coding stage, along with the MER performance analysis. The simulation results show that the conventional Gaussian-based compression techniques applied to a PAPR-reduced signal is not very robust to the statistical changes in the signal unless the signal distribution at the input of the Gaussian quantizer is not significantly affected. However, a significant gain is obtained when the quantizer is optimized with respect to the true distribution of the PAPR-reduced IQ samples.

关键词： Peak to average power ratio Time-domain analysis entropy coding Standards Modulation Digital video broadcasting Computer architecture C-RAN clipping compression quantization entropy coding MER OFDM PAPR reduction tone reservation DVB-T2 ATSC30

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Energy efficient image coding techniques for low power sensor nodes: A review

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AIN SHAMS ENGINEERING JOURNAL 2018年第4期9卷 2961-2972页

作者： Suseela, G. Phamila, Y. Asnath Victy VIT Univ Sch Comp Sci & Engn Chennai Campus Vellore Tamil Nadu India

Visual Sensors Networks (VSN) are spatially dispersed distributed networks, consisting of small sensing units and image sensors. They are scattered over a region to sense, collect and transfer data and are involved in domains such as environmental monitoring, surveillance and tracking. The resource restrictions imposed on sensor nodes are the challenges for image transmission. Sensor nodes are battery power supplied. The greatest operative solution is image compression for energy efficient image communication. With the advent of VSNs, energy-aware compression algorithms have gained wide attention. Since the application of the conventional standards are not energy beneficial. New strategies and mechanisms for power-efficient image compression algorithms are developed. The scope of this review is to provide a holistic review of such energy efficient image compression algorithms for camera equipped VSN. This survey enumerates the benefits and limitations of conventional image compression standards to latest compression technique developed and adapted for VSN. (C) 2018 Ain Shams University. Production and hosting by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://***/licenses/by-nc-nd/4.0/).

关键词： Image compression techniques DCT DWT Wireless sensor networks VSN entropy coding

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Adaptive rate control for Motion JPEG2000

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IET IMAGE PROCESSING 2009年第2期3卷 75-87页

作者： Li, L. Guo, M. Wang, Z. S. Chinese Acad Sci Comp Technol Inst Beijing 100190 Peoples R China Chinese Acad Sci Grad Univ Beijing 100049 Peoples R China

Rate and quality-constrained rate control is very effective for video applications, since it can maintain constant quality while eliminating local rate spikes. An adaptive rate control method based on image activity measures (ARCIAM) is proposed for Motion JPEG2000. The algorithm can efficiently adjust the compressed bit rates to meet the rate and quality constraints for different types of colour sequences. It predicts the rate-distortion (RD) slope thresholds for frames based on image activity measure (IAM) before entropy coding. Thus, the encoding of unnecessary coding passes can be avoided. Experimental results show that the proposed method can meet the quality and rate constraints, and can achieve quality performance comparable to post-compression rate distortion optimisation at the same bit rate. Under 3 bpp and 40 dB constraints, ARCIAM can reduce the total encoding time and tier-1 encoding time for sequences by more than 20 and 30%, respectively. Moreover, the memory requirement for buffering bit-streams and RD-slope information is reduced by more than 30% on average. Besides, the method can be incorporated into the line-based JPEG2000 encoding system easily, and has been implemented on Kakadu.

关键词： Motion JPEG2000 rate-distortion slope thresholds adaptive control image activity measure adaptive rate control method video coding image sequences Image and video coding video applications image-video coding image activity measures entropy coding image colour analysis colour sequences line-based JPEG2000 encoding system Video signal processing

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Large Alphabet Source coding Using Independent Component Analysis

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IEEE TRANSACTIONS ON INFORMATION THEORY 2017年第10期63卷 6514-6529页

作者： Painsky, Amichai Rosset, Saharon Feder, Meir Tel Aviv Univ Dept Stat IL-6997801 Tel Aviv Israel MIT Elect Res Lab Cambridge MA 02139 USA Tel Aviv Univ Dept Elect Engn IL-6997801 Tel Aviv Israel

Large alphabet source coding is a basic and well-studied problem in data compression. It has many applications, such as compression of natural language text, speech, and images. The classic perception of most commonly used methods is that a source is best described over an alphabet, which is at least as large as the observed alphabet. In this paper, we challenge this approach and introduce a conceptual framework in which a large alphabet source is decomposed into "as statistically independent as possible" components. This decomposition allows us to apply entropy encoding to each component separately, while benefiting from their reduced alphabet size. We show that in many cases, such decomposition results in a sum of marginal entropies which is only slightly greater than the entropy of the source. Our suggested algorithm, based on a generalization of the binary independent component analysis, is applicable for a variety of large alphabet source coding setups. This includes the classical lossless compression, universal compression, and high-dimensional vector quantization. In each of these setups, our suggested approach outperforms most commonly used methods. Moreover, our proposed framework is significantly easier to implement in most of these cases.

关键词： Data Compression Source coding entropy coding Independent Component Analysis

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FRACTAL BLOCK coding OF DIGITAL VIDEO

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IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS FOR VIDEO TECHNOLOGY 1994年第3期4卷 297-308页

作者： LAZAR, MS BRUTON, LT Department of Electrical and Computer Engineering University of Calgary Calgary AB Canada

A video coding method is proposed which is based upon fractal block coding. The method utilizes a novel three-dimensional partitioning of input frames for which a number of efficient block-matching search methods can be used, and permits spatio-temporal splitting of the input blocks to improve overall-encoding quality. After describing the basic fractal block coding algorithm, the details of the proposed three-dimensional algorithm are presented along with encoding and decoding results from two standard video test sequences, representative of video-conferencing data. These results indicate that average compression rates ranging from 40 to 77 can be obtained with subjective reconstruction quality of video-conferencing quality. The results also indicate that, in order to meet the compression rates required for very low bit rate coding, it is necessary to employ additional techniques such as entropy encoding of the 'fractal transformation coefficients.

关键词： block codes data compression digital signals fractals image coding image sequences teleconferencing video signals average compression rates block-matching search methods decoding digital video encoding quality entropy encoding fractal block coding fracta Teleconference compression ratio Digital video DEcoding image coding image sequences Data compression very low bit-rate coding entropy coding Video signals Fractals Block codes digital signals

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