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iterative estimation algorithms using conjugate function lower bound and minorization-maximization with applications in image denoising

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EURASIP JOURNAL ON ADVANCES IN SIGNAL PROCESSING 2008年第unknown期2008卷 429128-1-429128-12-0页

作者： Deng, Guang Ng, Wai-Yin La Trobe Univ Dept Elect Engn Bundoora Vic 3086 Australia Chinese Univ Hong Kong Dept Informat Engn Shatin Hong Kong Peoples R China

A fundamental problem in signal processing is to estimate signal from noisy observations. This is usually formulated as an optimization problem. Optimizations based on variational lower bound and minorization-maximization have been widely used in machine learning research, signal processing, and statistics. In this paper, we study iterative algorithms based on the conjugate function lower bound (CFLB) and minorization-maximization ( MM) for a class of objective functions. We propose a generalized version of these two algorithms and show that they are equivalent when the objective function is convex and differentiable. We then develop a CFLB/MM algorithm for solving the MAP estimation problems under a linear Gaussian observation model. We modify this algorithm for wavelet-domain image denoising. Experimental results show that using a single wavelet representation the performance of the proposed algorithms makes better than that of the bishrinkage algorithm which is arguably one of the best in recent publications. Using complex wavelet representations, the performance of the proposed algorithm is very competitive with that of the state-of-the-art algorithms. Copyright (c) 2008.

关键词： conjugate functions Lower bound Convexity Objective function image denoising Differentiable algorithms signal processing iterative algorithms

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iterative computing algorithms implemented in FPGA using ALTERA_CORDIC library as an example

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Procedia Computer Science 2024年 246卷 2380-2389页

作者： Paweł Poczekajło Koszalin University of Technology. ul Śniadeckich 2 75-453 Koszalin Poland

The article discusses the general issues of implementing pipelined and iterative algorithms. These are typical solutions for engineering algorithms implemented in hardware like reprogrammable systems. The authors focused on the implementation of such algorithms in field-programmable gate array (FPGA) circuits. Key aspects and advantages of pipelined processing were discussed. The focus was on an example CORDIC algorithm. Analyses of the iterative implementation using the ALTERA_CORDIC library were performed. Key parameters such as frequency and circuit occupancy were measured. Also, the obtained results were compared with the exact values - the errors were determined. Realizations based on 8-, 12- and 16-bits of fractional in fixed-position notation were analyzed.

关键词： iterative algorithms pipelined algorithms computing algorithms engineering computing CORDIC FPGA Altera library finite precision implementation occupation frequency

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Guest editorial - Capacity approaching codes, iterative decoding algorithms, and their applications

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IEEE Communications Magazine 2003年第8期41卷 100-101页

作者： M. Fossorier S. Olcer University of Hawaii

Presents the guest editorial for this issue of the publication.

关键词： iterative decoding iterative algorithms Turbo codes Parity check codes Error correction Power system modeling Engines Feedback Interference cancellation Multiuser detection

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A general formulation of constrained iterative restoration algorithms

A general formulation of constrained iterative restoration a...

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

作者： A. Katsaggelos J. Biemond R. Mersereau R. Schafer School of Electrical Engineering Georgia Institute of Technology Atlanta GA USA Department of Electrical Engineering Delft University of Technnology Delft Netherlands

This paper introduces a general formulation of constrained iterative restoration algorithms in which deterministic and/or statistical information about the undistorted signal and statistical information about the noise are directly incorporated into the iterative procedure. This a priori information is incorporated into the restoration algorithm by what we call "soft" or statistical constraints. Their effect on the solution depends on the amount of noise on the data; that is, the constraint operator is "turned off" for noiseless data. The development of the new iterative algorithm is based on results from regularization techniques for stabilizing ill-posed problems.

关键词： iterative algorithms Image restoration Signal restoration Signal processing algorithms Integral equations Signal processing Distortion Cameras Vectors Image sampling

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iterative distributed algorithms for real-time available transfer capability assessment of multiarea power systems

Iterative distributed algorithms for real-time available tra...

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IEEE General Meeting Power& Energy Society

作者： Jian-Hong Liu Chia-Chi Chu National Tsing Hua University Hsinchu TW

ISBN: (纸本)9781538622131;9781538622124

This paper studies iterative distributed algorithms for real-time available transfer capability (ATC) assessment in energy management systems of multiarea power systems. Since ATC calculations can be modeled as a special nonlinear optimal power-flow problem, iterative decomposition-coordination approaches based on constrained augmented Lagrangian methods can be applied. One special distributed scheme, called the auxiliary problem principle method, will be studied for distributed ATC assessment in this paper. A computation framework of this distributed algorithm is investigated. System partition with nonoverlapping and boundary sub-systems will also be studied. Simulations of several IEEE test systems will be conducted to validate the feasibility and the correctness of this distributed ATC. In addition, the real-time monitoring and reaction mechanism of this distributed algorithm will also be demonstrated by numerical experiments.

关键词： Distributed algorithms Real-time systems iterative algorithms Power systems Computational modeling Energy management

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iterative Scheduling algorithms

Iterative Scheduling Algorithms

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IEEE Annual Joint Conference: INFOCOM, IEEE Computer and Communications Societies

作者： M. Bayati B. Prabhakar D. Shah M. Sharma Stanford USA EECS Stanford USA EECS MIT China IBM Thomas J. Watson Research Center NY USA

The input-queued switch architecture is widely used in Internet routers due to its ability to run at very high line speeds. A central problem in designing an input-queued switch is the scheduling algorithm that decides which packets to transfer from ingress ports to egress ports in a given timeslot. It is desirable that such algorithms be iterative (so as to be pipelineable), distributed (allowing flexibility in hardware implementation) and are able to deliver high performance (in terms of throughput and delay). In practice, implementable algorithms have so far had limited success in combining all of the above properties. For example, the popular iSLIP algorithm is known to perform suboptimally, but it is commercially deployed mainly because it is iterative and distributed. The main contribution of this paper is the design and systematic analysis of two algorithms which, to the best of our knowledge, are the first high-performance iterative and distributed scheduling algorithms with possibility of efficient implementation. We first present an iterative, distributed and low-delay maximal throughput algorithm based on the celebrated "auction algorithm". This algorithm can be seen as a natural extension of iSLIP when queue-size information is allowed to be exchanged. The standard auction algorithm can take an unbounded number of iterations to converge in the worst case. However we show that under admissible Bernoulli i.i.d. traffic, our algorithm takes O(n 2 ) iterations, where n is the number of ingress/egress ports in the switch. Moreover for a switch with finite buffer-size, the algorithm allows for a graceful trade-off between running time and performance, which we verify by representative simulation results. Next, we propose and analyze a throughput-optimal, iterative and distributed scheduling algorithm influenced by Max-product belief propagation. Recently the problem of efficient transmission over multi-hop wireless networks has been formulated as that of findi

关键词： Scheduling algorithm iterative algorithms Switches Algorithm design and analysis Spread spectrum communication Throughput Traffic control Wireless networks Internet Packet switching

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Performance analysis of iterative scheduling algorithms for ATM input-queued switches

Performance analysis of iterative scheduling algorithms for ...

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International Symposium on Telecommunications

作者： S. Motoyama L.M. Ono M.C. Mavigno DT-FEEC-UNICAMP Sao Paulo Brazil

The performance of three iterative algorithms for input-queued ATM switches is studied. Mathematical models are proposed for throughput and cell delay analyses and compared to simulation results. The results show that... 详细信息

关键词： Performance analysis iterative algorithms Scheduling algorithm Asynchronous transfer mode Queueing analysis Switches Throughput Buffer storage Read-write memory Random access memory

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Parallel implementation of iterative and recursive algorithms: application on adaptive filtering in signal processing

Parallel implementation of iterative and recursive algorithm...

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IEEE International Symposium on Circuits and Systems (ISCAS)

作者： J.S. Castro P. Baylou 351 Cours de la Libération Equipe Signal et Image ENSER Bordeaux Talence France

A comparison is made of techniques of parallelization applied to iterative and recursive algorithms. These algorithms are analyzed considering three criteria to generate schedules. These schedules associated with a Boolean network model, allow the detection of communication conflicts. To reduce conflict possibility, the third criterion is proposed to take into consideration the communication constraints and their influence on the multiprocessor architecture.< >

关键词： iterative algorithms Filtering algorithms Adaptive filters Signal processing algorithms Partitioning algorithms Optimal scheduling Delay Scheduling algorithm Parallel processing Transversal filters

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Developing non-local iterative parallel algorithms for GIS on a workstation network

Developing non-local iterative parallel algorithms for GIS o...

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Euromicro Workshop on Parallel and Distributed Processing

作者： A. Clematis A. Coda M. Spagnuolo Instituto per la Matematica Applicate CNR Genoa Italy

The use of parallel computing is gaining increasing popularity in geographic information systems applications. There exists a class of spatial analysis algorithms that are based on local computation and are single step, hence leading to simple and efficient parallel code. For another class of algorithms it is not possible to make any assumption about the locality of computation, for example when extracting complex or global terrain features, and a number of iteration may be necessary to satisfy a convergence criteria, giving rise to non-local iterative algorithms. An example is the algorithm to extract drainage basins from digital terrain models. Despite the increasing difficulties there is an interest in parallelising non-local iterative algorithms. In this paper we present and compare different approaches to the parallelisation of non-local iterative algorithms on a workstation network using the Linda model of parallel programming.

关键词： Parallel algorithms Geographic Information Systems iterative algorithms Parallel processing Algorithm design and analysis Concurrent computing Data mining Convergence Digital elevation models Workstations

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A ringing metric to evaluate the quality of images restored using iterative deconvolution algorithms

A ringing metric to evaluate the quality of images restored ...

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IEEE International Conference on Systems Engineering

作者： M. Balasubramanian S.S. Iyengar J. Reynaud R.W. Beuerman Computer Science LSU USA Eye Centre LSUHSC USA Ophthalmology LSUHSC USA

iterative deconvolution algorithms exhibit increased ringing artifacts at higher number of iterations. Quantitative image analysis techniques such as optical flow algorithms are sensitive to these artifacts. We propose to use an image quality metric to identify the terminal step of iterative restoration algorithms. Frequency based metrics have difficulties in distinguishing the ringing artifacts from the image features. Spatial analysis techniques require extensive processing making them unsuitable for real-time image quality measurement as needed in iterative image restoration. We propose a novel ringing metric using binary morphological operators and demonstrate the method on the images of random cotton fibers acquired using white light confocal microscope.

关键词： Image restoration Deconvolution iterative algorithms Image analysis Image quality Optical sensors Image motion analysis Frequency Cotton Microscopy

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