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parallelization of symmetry detection algorithms on a network of workstations

MICROPROCESSORS AND MICROSYSTEMS 1997年第6期20卷 341-349页

作者： Parthiban, R Ravikumar, CP Kakarala, R Sivaswamy, J INDIAN INST TECHNOL DEPT ELECT ENGN NEW DELHI 110016 INDIA UNIV AUCKLAND DEPT ELECT & ELECT ENGN AUCKLAND 1 NEW ZEALAND

Detection of spatial symmetry is useful in several computer vision applications. Due to the real-time nature of the applications, it is important that symmetry detection algorithms be computationally efficient. Sequential algorithms for finding various types of planar symmetries in images are CPU-intensive, prompting us to look for fast parallel implementations. In this paper, we propose parallel algorithms for symmetry detection, and report an implementation on a distributed computing environment consisting of a network of Sun workstations. Experiments revealed close-to-linear speedup on a number of test images which we considered.

关键词： image symmetry detection parallel virtual machine parallel image processing

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All-optical subtracted joint transform correlator with a holographic interferometer

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APPLIED OPTICS 1997年第35期36卷 9205-9211页

作者： Yu, W Nakagawa, K Minemoto, T KOBE UNIV FAC ENGNNADA KUKOBEHYOGO 657JAPAN

A new, to our knowledge, subtracted joint transform correlator (SJTC) is proposed that has no digital processing in a computer. All processing for obtaining correlation signals between an object and multiple reference patterns were treated optically by use of a joint transform correlator with a holographic interferometer similar to the Mach-Zehnder one. The joint power spectrum of the reference patterns was subtracted from that of the input image (the object pattern plus the reference patterns), and the spurious correlation signals between the different reference patterns were removed. Because of the optical parallel computations of the Fourier spectra and the subtraction, the real-time SJTC is possible to achieve by use of only an optical system. An experimental arrangement of the system and system performances of the shift-invariant characteristics and discriminability are described. The results show the good performance of this system. (C) 1997 Optical Society of America.

关键词： joint transform correlator pattern recognition optical computing parallel image processing photorefractive effect

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Hardware support for shape decoding from 2D-region-based image representations

Hardware support for shape decoding from 2D-region-based ima...

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Conference on Multimedia Hardware Architectures 1997

作者： Privat, G LeHin, I France-Telecom Grenoble (France)

ISBN: (纸本)0819424323

Graphics systems have long been using standard libraries or APIs to insulate applications from implementation specifics. The same approach is applicable to natural image representations based on object primitives, such as proposed for MPEG4 standardization. The rendering of these image objects can be hidden behind APIs and supported either in hardware or software, depending on the level of representation they address, so that higher-level manipulation of these objects is made independent of the pixel level, We evaluate the trade-offs involved in the choice of these primitives to be used as pivotal intermediate representations. The example addressed is shape coding for image regions obtained from segmentation. Shape coding primitives based on either contour (chain codes), union of elementary patterns and alpha-plane are evaluated with regard to both the possibility to support them on different architecture models and the level of functionalities they make available.

关键词： image representation segmentation shape coding API parallel image processing

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A multiagent system for detecting concentric strias

A multiagent system for detecting concentric strias

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Conference on Applications of Digital image processing XX

作者： Ballet, P Rodin, V Tisseau, J Ecole Natl. d'Ingenieurs de Brest Technopôle Brest-Iroise 29608 Brest Cedex CP 15 France

ISBN: (纸本)0819425869

We present a method for detecting concentric strias which can be found in different natural ''objects'' (age-rings of tree, fish otolith growth rings, strias of some minerals,...). One of the major problems encountered during an automatic image processing is the lack of continuity perception in strias. We propose an approach to this continuity perception based on a multiagent system made up of reactive agents. These agents can move around on their environment which consists of an image made up of light and dark rings set out concentrically. Our multiagent system is made up of a set of agents named darkening agents and lightening agents. These agents follow either the light rings (lightening agents) or the dark rings (darkening agents) and act on the image. Their actions aim to reinforce the rings by stressing the contrasts allowing, thus, a reliable detection of these rings, even if they are discontinuous. Each agent has three sensors allowing it to obtain information about the environment. The sensors are made up of unit sensors returning the value of a pixel, The three sensors of an agent are a unit sensor allowing the agent to know if it is located on an already detected stria (sensor on the memory shared by all the agents), two disk-shaped sensors made up of unit sensors (sensors on the image). These two sensors return the sum of their unit sensors. They are located in front of the agent and distant one from the other. Those two disk-shaped sensors are used for determining the movements of the agent and, therefore, for detecting the rings. An agent, indeed, always tries to move where the values returned by the sensors is minimal. The suggested multiagent system has shown great robustness and adaptability for it can detect strias, even if they are discontinuous and the image noisy.

关键词： agent cooperation edge detection multiagent system parallel image processing

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DARPA benchmark image processing on SIMD parallel machines

DARPA benchmark image processing on SIMD parallel machines

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1996 IEEE 2nd International Conference on Algorithms and Architectures for parallel processing (ICA3PP 96)

作者： Cucchiara, R Piccardi, M Univ of Ferrara Ferrara Italy

ISBN: (纸本)0780335295

The aim of this paper is to present a comparative analysis of the execution times of low-level vision algorithms on two different SIMD parallel machines. The set of algorithms is part of the DARPA image Understanding benchmark, a widely-accepted platform for performance comparison of parallel systems in the field of computer vision. The considered computer architectures represent two opposite solutions in terms of granularity in approaching the SIMD paradigm, one with a coarse-grain array of floating-point processors and the other with a fine-grain array of single-bit processing elements. For these reasons, the set of algorithms was implemented on both systems taking into account machine specificities. In this work some insights into implementation issues and a comparative analysis of the assessed execution times are presented.

关键词： parallel image processing SIMD arrays benchmark

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Kydon: An autonomous, multi-layer image-understanding system: Lower layers

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ENGINEERING APPLICATIONS OF ARTIFICIAL INTELLIGENCE 1996年第1期9卷 43-52页

作者： Bourbakis, NG Mertoguno, JS UNIV CRETE RETHIMNONCRETEGREECE

In this paper, an autonomous, application-specific system architecture, called KYDON, is presented. The KYDON architecture consists of k layers of array processors. The lowest four layers compose the KYDON's low-level image-processing group, and the rest of the layers compose the higher-level processing groups. The interconnectivity at each array processor is based on a full hexagonal mesh structure. Each processing element (PE) of an array processor is a simple autonomous unit, including its own control unit (CU). This paper deals with the internal structural design of the PEs at the lower layers. It also provides a description of the low-level image-processing tasks performed by KYDON's lower-array processors. More specifically, the lowest layer is a 2-D photoarray, which captures images from the environment. The next three layers perform image processing and generate the graphic forms of the objects extracted from the input image. The next layers process the graphs provided by the lower layers in order to achieve an image understanding of the input image. An important feature of KYDON is that KYDON does not have any host computer or control processor to handle I/O and other miscellaneous tasks.

关键词： processor arrays application-specific array processor architectures parallel image processing autonomous systems distributed image representation

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A windowing approach to detecting line segments using Hough transform

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PATTERN RECOGNITION 1996年第2期29卷 255-265页

作者： Zhang, YF Webber, R UNIV WESTERN ONTARIO DEPT COMP SCILONDONON N6A 5B9CANADA

A new approach for using the Hough transform to detect line segments is presented. This approach is efficient in both space and time. Strategies combining the features of the intersection point [Ben-Tzvi, Leavers and Sandler, Proc. 5th Intl. Conf. image Anal. 152-159 (1990);Xu, Oja and Kultannen, Pattern Recognition Lett. 11, 331-338 (1990)] and dual plane [Conker, Comput. Vis. Graphics image Process. 43, 115-132 (1988)] methods are used to calculate the Hough transform. A dense set of small overlapping windows are used to restrict the pairs of image pixels that are evaluated. Experimental results indicate that this method reduces the time and space requirements significantly.

关键词： feature detection Hough transform parallel image processing algorithm analysis

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Analog VLSI motion projects at Caltech

Analog VLSI motion projects at Caltech

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Conference on Advanced Focal Plane Arrays and Electronic Cameras (AFPAEC 96)

作者： Kramer, J Indiveri, G Koch, C Univ. of Zurich (Switzerland) California Institute of Technology (United States)

ISBN: (纸本)0819423548

We present different compact analog VLSI motion sensors that compute the 1-D velocity of optical stimuli over a large range and are suitable for integration in focal plane arrays. They have been extensively tested and optimized for robust performance under varying light conditions. Since their output signals are only weakly dependent on contrast, they directly extract optical pow data from an image. Focal plane arrays of such sensors ore particularly interesting for application in single-chip systems that perform navigation tasks for moving robots or vehicles, where light weight, low power consumption, and real-time processing are crucial. Several monolithic motion-processing systems based on such velocity sensors have been built and tested. We describe here three chips, designed for the determination of the focus of expansion, the estimation of the time to contact, and the detection of motion discontinuities respectively. The first two systems have been specifically designed for vehicle navigation tasks. The choice of this application domain allows to make a priori assumptions about the optical pow field that simplifies the structure of the systems and improves their overall performance. The motion-discontinuity-detection system can be more generally used to segment images based on the velocities of its different domains with respect to the camera. It is particularly useful for background-foreground segregation in the case of ego-motion of an autonomous system in a static environment. Test results of the three systems are presented and their performance is evaluated.

关键词： motion sensors velocity sensors optical flow analog VLSI photoreceptors machine vision robot vision smart vision chips parallel image processing

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A GENERAL-PURPOSE MODEL FOR image OPERATIONS BASED ON MULTILAYER PERCEPTRONS

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PATTERN RECOGNITION 1995年第7期28卷 1083-1090页

作者： MOH, J SHIH, FY NEW JERSEY INST TECHNOL DEPT COMP & INFORMAT SCINEWARKNJ 07102

In this paper, we investigate the use of multilayer perceptrons with recurrent connections as the general purpose modules for image processing in parallel architectures. The networks are trained to carry out classification rules in image transformation. The training patterns can be derived from user-defined transformations or from loading the pair of a sample image and its target image when the prior knowledge of transformations is unknown. Applications of our model include image smoothing, enhancement, edge detection, noise removal, morphological operations, image filtering, etc. With a number of stages stacked up together we are able to apply a series of operations on the image. That means, by providing various sets of training patterns the system can adapt itself to the concatenated transformation. Besides, recurrent connections from output of the last stage to input of the first stage allow a repeated sequence of operations to be used.

关键词： RECURRENT NEURAL NETWORKS ERROR BACKPROPAGATION MULTILAYER PERCEPTRON MATHEMATICAL MORPHOLOGY parallel image processing

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ULTRA-FAST parallel CONTOUR TRACING, WITH APPLICATION TO THINNING

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PATTERN RECOGNITION 1994年第7期27卷 867-878页

作者： FERREIRA, A UBEDA, S EPFL INFORMAT THEOR LAB CH-1015 LAUSANNE SWITZERLAND UNIV JEAN MONNET TSI ST ETIENNE FRANCE

This paper proposes a parallel algorithm for contour tracking of binary pictures. Given an object contour composed by O(N) pixels, our algorithm computes in constant time the next layer of the contour of that object, using the weakest parallel model, i.e. an Exclusive Read Exclusive Write (EREW) parallel Random Access Machine (PRAM). As an application of the technique we show a work-optimal parallel thinning algorithm for binary pictures, based on Pavlidis' characterization of a skeleton. Our algorithm improves on previous solutions by producing a list of coordinates corresponding to the skeleton contour in O(N) time with O(N) processors in an EREW PRAM, where N is the width of the picture.

关键词： parallel image processing image CONTOUR TRACKING THINNING PRAM ALGORITHMS

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