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An Ultra-Low Complexity and High Efficiency Approach for Lossless Alpha Channel coding

IEEE TRANSACTIONS ON MULTIMEDIA 2020年第3期22卷 786-794页

作者： Zhao, Liping Lin, Tao Zhang, Dongyu Zhou, Kailun Wang, Shuhui Shaoxing Univ Dept Comp Sci & Engn Shaoxing 312000 Peoples R China Tongji Univ Inst VLSI Coll Elect & Informat Engn Shanghai 200092 Peoples R China

Alpha channel is being applied in an increasing number of mobile web applications on mobile devices that require ultra-low power consumption in all cases including compute-intensive video encoding and decoding. Thus, we propose an ultra-low coding complexity and high efficiency alpha channel lossless coding approach. A novel coding framework and four new coding schemes are proposed for alpha channel coding. The framework fuses a string matching technique and a proposed prediction coding scheme named bit-depth preserving prediction (BDPP) together to reduce the correlations within and between repeated identical patterns and neighboring pixels. To achieve a good tradeoff between complexity and efficiency, either the unmatchable bytes are coded directly or the BDPP residuals of unmatchable bytes are coded by a proposed bytewise entropy coding scheme named 0.5-1-2byte-size-code. The other string matching parameters are coded by another proposed bytewise entropy coding scheme named byte-size multi-variable-length-code. To speed up the string-matching search, we apply a fast string search scheme that combines special position search and hash-based search. For the selected typical 236 alpha test images, compared with x265 in the fastest configuration and lossless mode, the proposed lossless approach achieves 14.33% less total compressed bytes with only 2.75% encoding and 1.83% decoding runtime. The proposed approach also outperforms the conventional lossless coding techniques such as LZ4HC, ZLIB, and PNG.

关键词： Complexity theory Channel coding Image coding Standards Video coding Unified modeling language Image coding alpha channel coding string matching prediction coding variable length code

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Selective mapping for reduced complexity turbo channel estimation operating on highly time and frequency selective channels

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EUROPEAN TRANSACTIONS ON TELECOMMUNICATIONS 2010年第6期21卷 519-525页

作者： Chaabouni, Sihem Siala, Mohamed Sellami, Noura ISECS Sfax 3018 Tunisia SupCom Lab TECHTRA El Ghazala Ariana 2083 Tunisia ENIS Lab LETI Sfax 3038 Tunisia

In this paper, we consider a time division multiple access (TDMA) transmission of coded symbols over a time and frequency selective channel. At the receiver, a turbo-detector composed of a maximum a posteriori (MAP) equaliser and a MAP decoder is used. We give the expression of the MAP iterative burst-by-burst channel estimation algorithm using the Expectation-Maximisation (EM) algorithm. Since the obtained algorithm is complex, we propose to simplify it by neglecting the inter-symbol interference (ISI) term. In order to reduce the error caused by this simplification, we propose to use a candidate precoder at the transmitter chosen among a given set of precoders such that the selected precoded sequence leads to the minimum mean square value of the ISI neglected term. Simulations show that the performance of the approximate algorithm with precoding are almost similar to the performance of the exact algorithm. Copyright (C) 2010 John Wiley & Sons, Ltd.

关键词： MITIGATION ACTION PLANS Worm gears prediction coding simplification Turbo channel estimation manufacturing automation protocol algorithms time division multiple access Transmitters selective channel

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Lossless medical image compression by multilevel decomposition

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JOURNAL OF DIGITAL IMAGING 1996年第1期9卷 11-20页

作者： Kang, KS Park, HW KOREA ADV INST SCI & TECHNOL DEPT INFORMAT & COMMUN ENGNSEOUL 130012SOUTH KOREA

Lossless image coding is important for medical image compression because any information loss or error caused by the image compression process could affect clinical diagnostic decisions. This paper proposes a lossless compression algorithm for application to medical images that have high spatial correlation. The proposed image compression algorithm uses a multilevel decomposition scheme in conjunction with prediction and classification. In this algorithm, an image is divided into four subimages by subsampling. One subimage is used as a reference to predict the other three subimages. The prediction errors of the three subimages are classified into two or three groups by the characteristics of the reference subimage, and the classified prediction errors are encoded by entropy coding with corresponding code words. These subsampling and classified entropy coding procedures are repeated on the reference subimage in each level, and the reference subimage in the last repetition is encoded by conventional differential pulse code medulation and entropy coding. To verify this proposed algorithm, it was applied to several chest radiographs and computed tomography and magnetic resonance images, and the results were compared with those from well-known lossless compression algorithms. Copyright (C) 1996 by W.B. Saunders Company

关键词： lossless image compression medical image compression multilevel decomposition (MLD) prediction coding classification picture archiving and communication system (PACS)

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Dynamic resource allocation with precoding and joint coding scheme for limited feedback-based wireless multi-antenna multicast system

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IET COMMUNICATIONS 2013年第5期7卷 397-407页

作者： Chen, Lei Wang, Xiaoxiang He, Gaoning Beijing Univ Posts & Telecommun Minist Educ Key Lab Universal Wireless Commun Beijing 100876 Peoples R China Shenyang Agr Univ Sch Infarmat Engn Dept Commun Engn Shenyang 110044 Peoples R China Cent Res Inst Hua Wei Shanghai 200233 Peoples R China

In conventional multicast scheme (CMS), the total throughput of multicast group is constrained by the user with the worst channel quality. In order to overcome this problem of limited throughput, the authors introduce a resource allocation algorithm by exploiting layered coding combined with erasure correction coding for multicast services in the downlink of orthogonal frequency-division multiple access-based multi-antenna system. To reduce the feedback overhead of uplink, the authors design a novel transmission scheme with limited feedback. Then, the joint subcarrier and power allocation problem for the data of base layer and enhancement layers are formulated, which is shown to be non-deterministic polynomial-hard. Hence, in order to reduce the computational complexity, they propose a three-phase suboptimal algorithm. The algorithm is designed to maximise the system throughput, whereas at the same time guarantee the quality of services (QoS) requirements of all multicast groups. It is composed of precoding scheme, proportional fairness subcarrier allocation algorithm and modified water-filling power allocation algorithm with QoS guarantees (MWF-Q). To further decrease the complexity of MWF-Q, a power allocation algorithm with increased fixed power allocation algorithm with QoS guarantees is introduced. Simulation results show that the proposed algorithms based on limited feedback scheme significantly outperform CMS and any other existing algorithm with full feedback. Moreover, the proposed scheme can efficiently reduce 50% of the full feedback overhead.

关键词： Quality of service BASE COURSE Allocation Algorithm Feedback Meltdown Resource utilization management of resources prediction coding Multicast multiple antenna power splitting

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Hybrid precoding with compressive sensing based limited feedback in massive MIMO systems

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TRANSACTIONS ON EMERGING TELECOMMUNICATIONS TECHNOLOGIES 2016年第12期27卷 1672-1678页

作者： Jiang, Dongmei Natarajan, Balasubramaniam Qingdao Univ Dept Commun Engn 308 Ningxia Rd Qingdao 266071 Peoples R China Kansas State Univ Dept Elect & Comp Engn Manhattan KS 66506 USA

Massive multiple-input multiple-output (MIMO) systems are an enabling technology for high capacity 5G cellular networks. However, the high hardware complexity and power consumption make it difficult to apply conventional MIMO precoding schemes in massive MIMO. Additionally, thanks to the large channel dimension, applying traditional limited feedback schemes for obtaining channel state information at the transmitter is a challenge. In this paper, we develop a low-complexity hybrid precoding scheme for multiuser massive MIMO system in mmWave communication. We design the analog beamformer as the conjugate transpose of the downlink channel from base station to the users. Then zero-forcing baseband processing is applied over the effective channel. We get the optimal power allocation policy and compare its performance with average power allocation based on channel state information at transmitter. The channel state information at transmitter is obtained via a compressive sensing based limited feedback strategy. The effectiveness of hybrid precoding relies on the feedback quality of channel state information, which relies on the compression ratio. We quantify the impact of compression ratio on precoder performance and derive an upper bound on the sum rate. Simulation results illustrate the performance of our proposed scheme and the effect of compressive sensing based limited feedback.

关键词： compression ratio power splitting prediction coding channel dimension Transmitter Channel state information multiple input multiple output systems Feedback Compressed sensing

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COMPACT CODER FOR COMPONENT COLOR-TELEVISION

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IEEE TRANSACTIONS ON COMMUNICATIONS 1990年第2期38卷 223-232页

作者： BRAINARD, RC PURI, A AT and T Bell Laboratories Inc. Holmdel NJ USA

A study of predictive coding of component TV signals for compression to transmit at rates that give good picture quality is reported. Designing predictors for minimum mean square prediction error is effective, both for luminance and chrominance signals. Predictors designed in this manner were found to be as good as or better than all other predictors tested. Quantizers designed for minimum mean square system error were primarily used in this study. A programmable testbed was built to permit quick comparisons. Predictors were compared on the testbed using a 2-b quantizer in order to have adequate system error to display visible differences. For simple intrafield coding, component signals compressed for transmission at 30 Mb/s gave about equivalent quality to an NTSC composite signal coded directly for transmission at 45 Mb/s. With 45-Mb/s transmission, component signal coding showed no detectable degradation on close inspection of real pictures. Maximum chrominance changes on test patterns yield visually detectable chrominance slope overload.

关键词： Transmission components prediction coding Chromaticity Systematic errors quantizer luminance Mean square error test pattern mean square

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Minimum mean square error vector precoding

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EUROPEAN TRANSACTIONS ON TELECOMMUNICATIONS 2008年第3期19卷 219-231页

作者： Schmidt, David A. Joham, Michael Utschick, Wolfgang Tech Univ Munich Associate Inst Signal Proc D-80290 Munich Germany

We derive the minimum mean square error (MMSE) solution to vector precoding for frequency flat multiuser scenarios with a centralised multi-antenna transmitter. The receivers employ a modulo operation, giving the transmitter the additional degree of freedom to choose a perturbation vector. Similar to existing vector precoding techniques, the Optimum perturbation vector is found with a closest point search in a lattice. The proposed MMSE vector precoder does not, however, search for the perturbation vector resulting in the lowest unsealed transmit power, as proposed in all previous contributions on vector precoding, but finds an optimum compromise between noise enhancement and residual interference. We present simulation results showing that the proposed technique outperforms existing vector precoders, as well as the MMSE Tomlinson-Harashima precoder, and compare the turbo-coded performance to the capacity of the broadcast channel. Copyright (C) 2007 John Wiley & Sons, Ltd.

关键词： prediction coding broadcast channels Transmitter Cloning Vectors Mini Mental State Examination Degree of freedom Transmitter power Transmitters Mean square error perturbation

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A Novel High-Capacity Data Hiding in Encrypted Images Based on Compressive Sensing Progressive Recovery

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IEEE SIGNAL PROCESSING LETTERS 2020年第0期27卷 296-300页

作者： Xiao, Di Li, Fei Wang, Mengdi Zheng, Hongying Chongqing Univ Coll Comp Sci Chongqing 400044 Peoples R China

Due to the emergence of visual privacy issues, encrypted image processing has attracted a lot of attention. Data hiding in encrypted images (DHEI) is an effective method to embed secret data in the encrypted domain and protect the image privacy. However, existing methods do not allow a large amount of embedding capacity. In this letter, we propose a novel DHEI scheme utilizing prediction coding based on compressive sensing (CS) progressive recovery. The original image is pre-processed using CS prediction technique to create spare room, and then the image is encrypted and sent to the data hider. Furthermore, the data hider could embed secret data into Most Significant Bits (MSBs) of the corresponding locations. In the decoding phase, the embedded data can be extracted without any distortion and the original image could be reconstructed. Experimental results demonstrate that our scheme can achieve a higher embedding capacity than other state-of-the-art schemes while keeping a considerable recovered image quality.

关键词： Data hiding encrypted domain compressive sensing prediction coding embedding capability

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Predictive coding and Pitch Processing in the Auditory Cortex

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JOURNAL OF COGNITIVE NEUROSCIENCE 2011年第10期23卷 3084-3094页

作者： Kumar, Sukhbinder Sedley, William Nourski, Kirill V. Kawasaki, Hiroto Oya, Hiroyuki Patterson, Roy D. Howard, Matthew A., III Friston, Karl J. Griffiths, Timothy D. UCL Wellcome Trust Ctr Neuroimaging London WC1N 3BG England Newcastle Univ Sch Med Newcastle Upon Tyne NE1 7RU Tyne & Wear England Univ Iowa Hosp & Clin Iowa City IA 52242 USA Univ Cambridge Cambridge CB2 1TN England

In this work, we show that electrophysiological responses during pitch perception are best explained by distributed activity in a hierarchy of cortical sources and, crucially, that the effective connectivity between these sources is modulated with pitch strength. Local field potentials were recorded in two subjects from primary auditory cortex and adjacent auditory cortical areas along the axis of Heschl's gyrus (HG) while they listened to stimuli of varying pitch strength. Dynamic causal modeling was used to compare system architectures that might explain the recorded activity. The data show that representation of pitch requires an interaction between nonprimary and primary auditory cortex along HG that is consistent with the principle of predictive coding.

关键词： Social Hierarchy prediction coding Pitch Perception Primary Auditory Cortex controllable pitch

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Active Inference and Learning in the Cerebellum

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NEURAL COMPUTATION 2016年第9期28卷 1812-1839页

作者： Friston, Karl Herreros, Ivan UCL Wellcome Trust Ctr Neuroimaging London WC1N 3BG England Univ Pompeu Fabra Catalan Inst Adv Res Dept Technol Barcelona 08018 Spain

This letter offers a computational account of Pavlovian conditioning in the cerebellum based on active inference and predictive coding. Using eyeblink conditioning as a canonical paradigm, we formulate a minimal generative model that can account for spontaneous blinking, startle responses, and (delay or trace) conditioning. We then establish the face validity of the model using simulated responses to unconditioned and conditioned stimuli to reproduce the sorts of behavior that are observed empirically. The scheme's anatomical validity is then addressed by associating variables in the predictive coding scheme with nuclei and neuronal populations to match the (extrinsic and intrinsic) connectivity of the cerebellar (eyeblink conditioning) system. Finally, we try to establish predictive validity by reproducing selective failures of delay conditioning, trace conditioning, and extinction using (simulated and reversible) focal lesions. Although rather metaphorical, the ensuing scheme can account for a remarkable range of anatomical and neurophysiological aspects of cerebellar circuitryand the specificity of lesion-deficit mappings that have been established experimentally. From a computational perspective, this work shows how conditioning or learning can be formulated in terms of minimizing variational free energy (or maximizing Bayesian model evidence) using exactly the same principles that underlie predictive coding in perception.

关键词： Epicoccum Statistical Validity simulating Blinking prediction coding Trace conditioning Learning Cerebellum face validity Conditioning

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