Browsing by Author "Parker, J.R."
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- ItemOpen AccessANALYSIS AND SIMULATION OF A COMMON BUS MULTIPROCESSOR(1987-06-01) Parker, J.R.No abstract
- ItemOpen AccessAN APPROACH TO LICENSE PLATE RECOGNITION(1996-10-01) Parker, J.R.; Federl, P.Here we describe a project that deals with license plate location in raster images. The algorithm takes a raster image as input, and yields the position of a plate in the image. After the position is determined, the algorithm can determine the locations of the license plate characters, which could be easily combined with an OCR algorithm to convert the license plate number into an ASCII string.
- ItemOpen AccessAN APPROACH TO STELLAR PHOTOMETRY USING SIMULATED ANNEALING(1995-04-01) Parker, J.R.; Groisman, G.Simulated annealing can be quite effectively used to fit functions of many parameters to a set of data. This paper discusses the application of simulated annealing to the fitting of Moffat functions to crowded field star images. Overlapping star profiles can be fit simultaneously and missed stars can be located based on the $x sup 2$ value of the fit, and the resulting functional model yields excellent photometric results. This method has been integrated into a photometry system which allows the user to select the accuracy of the results at the expense of time needed to perform the calculations, and is but one example of such an application.
- ItemOpen AccessCHARACTER THINNING USING A DIFFERENCE OPERATOR(1985-06-01) Parker, J.R.A character thinning method is presented that makes use of edge directions as determined by a difference operator. A preprocessing stage, also using a difference, minimizes the production of tails and the necking effect.
- ItemOpen AccessCOMPUTER ASSISTED PHOTOMETRY USING SIMULATED ANNEALING(1993-02-01) Parker, J.R.; Groisman, G.The computationaltechnique known as simulated annealing, which originally was used to solve problems in combinatiorial optimization, can be quite effectively used to fit functions of many parameters to a set of data. This paper discusses the application of simulated annealing to the fitting of Moffat functions to crowded field star images. Overlapping star profiles can be fit simultaneously and missed stars can be located based on the $X sup 2$ value of the fit, and the resulting functional model yields excellent photometric results. This method has been integrated into a photometry system which allows the user to select the accuracy of the results at the expense of time needed to perform the calculations.
- ItemOpen AccessDATA MODELING IN SCIENTIFIC IMAGES USING SIMULATED ANNEALING(1993-02-01) Parker, J.R.; Groisman, G.One way to measure objects in some classes of scientific image is to model the objects by functions and then make the measurements on the functions. This works especially well for images that contain information in the form of relationships between grey level pixels. Here, the use of a Moffat function as a data model is explored, as is the use of simulated annealing to fit many instances of this function to the data in the image. Two examples are presented: stellar photometry, a natural application for the Moffat function, and reading DNA sequencing gels.
- ItemOpen AccessDESIGN AND ANALYSIS OF A MULTIPROCESSOR FOR IMAGE PROCESSING(1990-08-01) Parker, J.R.; Ingoldsby, T.R.No Abstract
- ItemOpen AccessDISTRIBUTED FORCE-BASED THINNING AND A GENERAL DISTRIBUTION METHOD(1993-02-01) Molaro, D.; Parker, J.R.; Jennings, C.A recently developed thinning algorithm, based on computing repulsive `forces' acting on each object pixel, produces nice skeletons, but involves some very intensive computations. As a result, the method takes a long time to thin any real image, when compared against other existing methods. It can be made practical by distributing the computation across a network of workstations. This has applications to other computationally difficult image processing and vision algorithms, and has been generalized and made relatively simple to do.
- ItemOpen AccessEXTRACTING VECTORS FROM RASTER IMAGES(1987-02-01) Parker, J.R.It is often true that a user of computer images is interested in only a few kinds of features. In particular, in a class of pictures called line images, the major feature is a line or vector. Raster representations of line images, while common, are quite wasteful of storage and are difficult to manipulate. If the vectors could be extracted reliably from the raster image, then rotation, scaling, plotting, and many other operations could be speeded up enormously.
- ItemOpen AccessFORCE-BASED THINNING STRATEGY WITH SUB-PIXEL PRECISION(1993-02-01) Molaro, D.; Parker, J.R.; Jennings, C.Most vision researchers would agree that the medial axis transform does not yield an ideal, or in some cases even acceptable, skeleton. For example, single pixel irregularities can produce gross changes in an otherwise simple skeleton. The problem of defining what is meant by skeleton and skeletal pixel is one that has been rarely addressed, but seems important. Here, a thinning strategy is proposed that is based on a definition of a 'skeletal pixel'. The basic idea is that a skeleton is a global property of a binary object, and that the boundary should be used to locate the skeletal pixels.
- ItemMetadata onlyA GENERAL CHARACTER TO INTEGER CONVERSION METHOD(1982-04-01) Parker, J.R.Most programs which involve character to integer conversion fail to detect integer overflow correctly. This paper describes some of the pitfalls of not recognizing overflow, and presents a correct method for doing so in an arbitrary base for any precision.
- ItemOpen AccessA GENETIC ALGORITHM FOR STELLAR PHOTOMETRY(1995-04-01) Parker, J.R.A class of scientific images, which we will call blot images, contains information in the form of relationships between grey level pixels. One way to extract this information is to fit model functions to the objects in the image. We have explored the use of a Moffat function as a data model, and use a genetic algorithm to fit many instances of this function to the data in the image. The example of stellar photometry is used, a natural application for the Moffat function.
- ItemOpen AccessGENETIC OPERATORS ON FLOATING POINT PARAMETERS(1995-04-01) Parker, J.R.The single bit mutation and one point crossover operations are most commonly implemented on a chromosome that is encoded as a bit string. If the actual arguments are real numbers this implies a fixed point encoding and decoding each time an argument is updated. A method is presented here for applying these operators to floating point numbers directly, eliminating the need for bit strings. The result accurately models the equivalent bit string operations, and is faster overall.
- ItemOpen AccessGREY LEVEL THRESHOLDING IN BADLY ILLUMINATED IMAGES(1990-06-01) Parker, J.R.Most grey level thresholding methods produce very good results in situations where the illumination gradient in the original raster image is regular and not too large. In other cases, such as a large linear change in illumination, a satisfactory bi-level image cannot be produced. One approach is to locate object pixels first, and then grow regions around these, generating a threshold value for each pixel.
- ItemOpen AccessHANDPRINTED DIGIT RECOGNITION BY STROKE TRACING(1995-04-01) Parker, J.R.A structural method of recognizing handprinted digits is described, in which the strokes comprising the digits are decomposed into line segments. The lines are matched against stroke templates, beginning at a `pen down' point and traced as far as possible. Both direction and length are important to the template match. Error rates of 3.3% are reported.
- ItemOpen AccessHIDDEN OBJECT RECONSTRUCTION FROM ACOUSTIC SLICES(1996-10-01) Parker, J.R.; Attia, E.N.A method for reconstructing 3D models from cross-sectional seismic signals, which could be used in visualizing underground objects, is presented. The new algorithm starts with preprocessing the sonar images by thresholding, segmenting, contour finding, point sampling and then triangulating. The main objective of this algorithm was to produce the smoothest possible model for branching bodies taking into consideration that the slices might be far apart in reality and consequently a novel branching/interpolation technique was used that proved superior to existing methods and at the same time did not need involvement of the user at any stage. Seismic simulations have been used to test the algorithm and we succeeded in reconstructing the tomb of Tut Ankh Amen (An Egyptian Pharaoh) from simulated slices.
- ItemOpen AccessA HIGH-LEVEL PROGRAMMING LANGUAGE FOR DIGITAL MORPHOLOGY(1998-03-01) Parker, J.R.A system for digital morphology is presented in which morphological operators are implemented as basic operation in a programming language, and where basic data types include pixels and images. The resulting language can be used effectively for prototyping morphological software and for teaching the principles.
- ItemOpen AccessA MICROPROGRAMMING SIMULATOR FOR INSTRUCTIONAL USE(1983-10-01) Parker, J.R.; Becker, KatrinNo Abstract
- ItemOpen AccessMULTIPLE SENSORS, VOTING METHODS AND TARGET VALUE ANALYSIS(1998-02-01) Parker, J.R.Voting techniques for high level sensor/data fusion are explored here, with examples from character recognition and target value analysis. High degrees of reliability can be achieved, and the method can be applied to various kinds of data. The only requirement is that a ranking of the targets be extracted from the sensors.