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IEEE/SP Workshop on Statistical Signal processing (SSP)

作者： S.S. Agauan T.A. Baran K.A. Panetta Dept. of Electr. Eng. Texas Univ. San Antonio TX USA Tufts University Electrical and Computer Engineering Medford MA USA

A method for the lossy compression of multivalued images using transform-based Boolean minimization is described. Blocks in bit-planes of an image are minimized, and the results of these minimizations are used to detect and reduce noise (sandy regions) and spatial complexity in the blocks. Specifically, the techniques of "minterm uniformalization" and "minterm quantization and thresholding" are presented as methods of discarding perceptually insignificant information from a minimized representation of an image and use data readily available from minimization without the calculation of complicated measures. Experimentally, results comparable to JPEG and better than existing binary techniques can be expected. Fast algorithms may be used, no multiplications are required, and decompression is performed without an inverse transform. Therefore, an emphasis is placed on the use of these algorithms for low-complexity or very high-speed hardware implementations for communications, for distributed and parallel sensor and computing applications, as well as for database storage.

关键词： image coding Noise reduction Minimization methods Educational institutions image databases image storage Transform coding Boolean functions Quantization Hardware

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Iso-splatting: a point-based alternative to isosurface visualization

Iso-splatting: a point-based alternative to isosurface visua...

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Pacific Conference on Computer Graphics and Applications

作者： C.S. Co B. Hamann K.I. Joy Center for Image Processing and Integrated Computing (CIPIC) Department of Computer Science University of California USA

We present a new approach to isosurface visualization that we call "iso-splatting." We use point primitives for representing and rendering isosurfaces. The method consists of two steps. In the first step, point samples are generated throughout the volumetric domain of a scalar function. In the second step, these points are projected onto the isosurface of interest. We render the resulting point set using a surface splatting algorithm. The method can be extended to out-of-core or parallel environments. Our results show that this method can offer much greater time and space efficiency when compared with standard triangle-based methods, thereby supporting higher levels of interactivity. Parts of the algorithm can be accelerated using graphics hardware. One key advantage of this approach is that, since extraction computations are divided into two smaller phases, work can be distributed to exploit all available resources.

关键词： Isosurfaces Visualization Rendering (computer graphics) Computational geometry Fuels image processing Computer science Acceleration Graphics Hardware

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Remote survey of large-scale braided, gravel-bed rivers using digital photogrammetry and image analysis

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INTERNATIONAL JOURNAL OF REMOTE SENSING 2003年第4期24卷 795-815页

作者： Westaway, RM Lane, SN Hicks, DM Halcrow Grp Ltd Geomatics & GIS Swindon SN4 0QD Wilts England Univ Leeds Sch Geog Leeds LS2 9JT W Yorkshire England Natl Inst Water & Atmospher Res Ltd Christchurch New Zealand

The use of conventional survey methods to monitor large, gravel river beds has traditionally led to a reliance on repeat measurements of cross-sections which, unless very closely spaced, may give unreliable information about three-dimensional channel morphology and morphological change. Provided certain technological limitations can be overcome, remote survey techniques, such as digital photogrammetry and airborne laser scanning, remove the spatial and temporal constraints typically associated with ground-based surveys, allowing high spatial resolution, distributed, elevation mapping of gravel river beds. This paper develops the use of digital photogrammetry for the survey of a 3.3 km reach of the braided Waimakariri River, New Zealand, which, when combined with image analysis of water colour to infer water depth, provides a Digital Elevation Model (DEM) of the entire river bed. Central to the successful application of this method is DEM post-processing. Errors take two forms: (i) individual point errors associated with incorrect stereo-matching during automated data collection;and (ii) spatially-variable systematic errors that are associated with uncertainties in sensor position and orientation as determined during the bundle adjustment. An automated post-processing procedure is developed to deal with individual point errors and this improves DEM surface quality in terms of accuracy, precision and internal reliability. Systematic errors in the final DEM surface were reduced by applying a simple correction based on surveyed photo-control point elevations.

关键词： Natural resources exploration

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Well-posed anisotropic diffusion for image denoising

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IEE PROCEEDINGS-VISION image AND SIGNAL processing 2002年第4期149卷 244-252页

作者： Ceccarelli, M De Simone, V Murli, A Univ Sannio I-82100 Benevento Italy CNR CPS Ctr Res Parallel Comp & Supercomp Naples Italy Univ Naples Federico II Dept Math & Applicat Naples Italy

A nonlinear iterative smoothing filter based on a second-order partial differential equation is introduced. It smooths out the image according to an anisotropic diffusion process. The approach is based on a smooth approximation of the total variation (TV) functional which overcomes the non-differentiability of the TV functional at the origin. In particular, the authors perform linear smoothing over smooth areas but selective smoothing over candidate edges. By relating the smoothing parameter to the time step, they arrive at a CFL condition which guarantees the causality of the discrete scheme. This allows the adoption of higher time discretisation steps, while ensuring the absence of artefacts deriving from the non-smooth behaviour of the TV functional at the origin. In particular, it is shown that the proposed approach avoids the typical staircase effects in smooth areas which occur in the standard time-marching TV scheme.

关键词： causality well-posed anisotropic diffusion Functional analysis (numerical analysis) higher time discretisation steps image denoising total variation functional second-order partial differential equation image restoration problem image restoration selective smoothing Computer vision and image processing techniques Filtering methods in signal processing random Gaussian noise Interpolation and function approximation (numerical analysis) functional analysis Optical, image and video signal processing iterative methods filtering theory Differential equations (numerical analysis) Gaussian noise discrete scheme nonlinear filters CFL condition linear smoothing nonlinear iterative smoothing filter smoothing methods partial differential equations

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A new model for static mapping of parallel applications with task and data parallelism 16

A new model for static mapping of parallel applications with...

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16th International parallel and distributed processing Symposium, IPDPS 2002

作者： Roig, C. Ripoll, A. Senar, M.A. Guirado, F. Luque, E. Universitat de Lleida Dept. of CS Jaume II 69 Lleida25001 Spain Universitat Autònoma de Barcelona Dept. of CS BellaterraBarcelona08193 Spain

ISBN: (纸本)0769515738

The efficient mapping of parallel tasks is essential in order to exploit the gain from parallelisation. In this work, we focus on modelling and mapping message-passing applications that are defined by the programmer with an arbitrary interaction pattern among tasks. A new model is proposed, known as TTIG (Temporal Task Interaction Graph), which captures not only computation and communication costs, but also the percentages of concurrency between tasks. From this model, a mapping strategy is developed that minimises expected execution time by properly exploiting task parallelism. The effectiveness of this approach has been proven for a real image-processing application on a cluster of PCs. © 2002 IEEE.

关键词： mapping algorithms mapping of image-processing application modelling message-passing applications static mapping task and data parallelism

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Effects of migration methods in parallel distributed parameter-free genetic algorithm

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ELECTRONICS AND COMMUNICATIONS IN JAPAN PART ii-ELECTRONICS 2002年第11期85卷 71-80页

作者： Adachi, S Sawai, H Kansai Adv Res Ctr Commun Res Lab Kobe Hyogo 6512401 Japan Commun Res Labs Intelligent Commun Div Koganei Tokyo 1848795 Japan

The effects of migration in parallel distributed processing of a parameter-free genetic algorithm (PfGA) that does not require establishing genetic parameters such as the initial population size, crossing-over rate, and mutation rate are discussed. This PfGA is a compact and robust algorithm characterized by the fact that it extracts one local population (subpopulation) from the entire search space and searches the prospective space while varying the local population size adaptively. The algorithm has been implemented on parallel computers using a hierarchical parallel-distributed architecture of the PfGA that includes migration methods. As a result of performance evaluation using a general functional optimization (minimum value search) problem including the international benchmark problem, it has been verified that the search success rate is maintained or improved, and that increasing the number of local populations by using the proposed migration selection methods can effectively reduce the number of evaluations required for success. (C) 2002 Wiley Periodicals, Inc.

关键词： parameter-free genetic algorithm (PfGA) parallel distributed processing migration selection methods function optimization

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distributed constraint satisfaction via a society of hill-climbers

Distributed constraint satisfaction via a society of hill-cl...

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作者： Dozier, Gerry Department of Computer Science and Software Engineering Auburn University AL 36849-5347 United States

ISBN: (纸本)1889335185

In this paper, we compare two modified versions of Yokoo's distributed breakout hill-climbing algorithm (DBA) [6], mDBA-I and mDBA-ii, along with six evolutionary computations referred to as societies of hill-climbers (SoHC) [3] on 400 randomly generated distributed constraint satisfaction problems (disCSPs). Each SoHC is composed of S instances of mDBA-ii running in parallel, where S represents the society size. The S hill-climbers communicate with one another through a distributed list of breakout elements which represent nogoods discovered at local minima. Our results show that larger society sizes are better in terms of convergence percentage and average cycle performance. However, this better performance comes at a cost of increased constraint checks and message sizes.

关键词： Constraint satisfaction problems

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Residue Number System's (RNS) Non-modular Operations Efficient Implementation Based on Chinese Remainder Theorem ii (CRT ii)

Residue Number System's (RNS) Non-modular Operations Efficie...

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作者： Al-Radadi, Eid Ayad Wayne State University

学位级别：Ph.D.

Residue number system (RNS) is an alternative method of number representation, it is basically different from weighted number system such as decimal and binary. The RNS is based on modular arithmetic. The RNS system has attracted many researchers in the last decade. The researchers have been focused on the theory of improving the RNS system and applying the RNS in some application areas, such as digital signal processing, fast fourier transform (FFT), digital filter, and image processing. The RNS system is inherently parallel, modular, and fault isolating. In addition, the main advantage of RNS system is the carry free operation in modular arithmetic operation: addition, subtraction, and multiplication. On the other hand, in non-modular operation such as, magnitude comparison, sign detection, and overflow detection are very slow and time consuming. Therefore, the RNS system is not widely used. Also the implementation of the RNS algorithms require efficient modular adders, and modular multipliers. This dissertation presents algorithms and implementation techniques that improve the RNS non-modular operations. New methods are proposed for sign detection, RNS to Binary and Binary to RNS converters, number comparison, and overflow detection. These methods are based on chinese remainder theorem ii (CRT ii). Also in this dissertation new design architectures for modulo 2n-a adders and modulo 2n-a multipliers are presented, where a = 1 or 2m + 1 and m < n.

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AVHRR rectification using orbital navigation and image matching

AVHRR rectification using orbital navigation and image match...

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image and Signal processing for Remote Sensing Vii

作者： Marçal, André R.S. Borges, Janete Faculdade de Ciências Universidade do Porto Departamento de Matematica Aplicada Rua do Campo Alegre 687 4169-007 Porto Portugal

Polar orbital satellites with low spatial resolution sensors, such as the AVHRR, provide global coverage with a short repetition period. The data is directly transmitted to ground stations, and can be distributed immediately after data acquisition. Near real time applications can be implemented if the adequate processing tools are available. One task usually needed is the geometric correction of image data. Automatic methods, based on satellite orbital parameters, can in some cases provide satisfactory results. However, the identification of Ground Control Points (GCPs) is generally required in order to achieve registration errors below the pixel size. A fully automatic method for the geometric registration of AVHRR data is proposed here. The method comprises four stages: (i) an initial image transformation based on orbital parameters, (ii) image segmentation of this image into 3 main classes (land, water, cloud) and 9 additional classes of mixed water and land at various levels, (iii) automatic GCP collection by image matching, (iv) final image production combining both orbital and GCP information. The method was tested on ten images of the Iberian Peninsula, and proved effective in accurately geo-referencing sub-sections of an AVHRR scene of medium dimension in a few minutes.

关键词： Radiometers

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parallelization and performance of 3D ultrasound imaging beamforming algorithms on modern clusters

Parallelization and performance of 3D ultrasound imaging bea...

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Conference Proceedings of the 2002 International Conference on Supercomputing

作者： Zhang, Fan Bilas, A. Dhanantwari, Amar Plataniotis, Kostas N. Abiprojo, Robert Stergiopoulos, Stergios Dept. of Electrical and Comp. Eng. University of Toronto 10 King's College Road Toronto Ont. M5S3G4 Canada

Recently there has been a lot of interest in improving the infrastructure used in medical applications. In particular, there is renewed interest on non-invasive, high-resolution diagnostic methods. One such method is digital, 3D ultrasound medical imaging. Current state-of-the-art ultrasound systems use specialized hardware for performing advanced processing of input data to improve the quality of the generated images. Such systems are limited in their capabilities by the underlying computing architecture and they tend to be expensive due to the specialized nature of the solutions they employ. Our goal in this work is twofold: (i) To understand the behavior of this class of emerging medical applications in order to provide an efficient parallel implementation and (ii) to introduce a new benchmark for parallel computer architectures from a novel and important class of applications. We address the limitations faced by modern ultrasound systems by investigating how all processing required by advanced beamforming algorithms can be performed on modern clusters of high-end PCs connected with low-latency, high-bandwidth system area networks. We investigate the computational characteristics of a state-of-the-art algorithm and demonstrate that today's commodity architectures are capable of providing almost-real-time performance without compromising image quality significantly.

关键词： parallel processing systems

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