Let a vector of probabilities be associated with every node of a graph. These probabilities define a random variable representing the possible labels of the node. Probabilities at neighboring nodes are used iterativel...
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Let a vector of probabilities be associated with every node of a graph. These probabilities define a random variable representing the possible labels of the node. Probabilities at neighboring nodes are used iteratively to update the probabilities at a given node based on statistical relations among node labels. The results are compared with previous work on probabilistic relaxation labeling, and examples are given from the image segmentation domain. References are also given to applications of the new scheme in text processing.
Many applications in picture processing.require accurate slope estimation. A brief survey of these applications is followed by discussion of the Sobel edge detection operator. The Sobel operator is very fast and simpl...
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Many applications in picture processing.require accurate slope estimation. A brief survey of these applications is followed by discussion of the Sobel edge detection operator. The Sobel operator is very fast and simple; however, it is inherently biased as a function of true slope value and displacement of the true edge from center of the processing.window. An iterative version of the operator is presented which reduces this bias with only a moderate increase in required processing.
A picture digitization grid based on logarithmic spirals rather than Cartesian coordinates is presented. Expressing this curvilinear grid as a conformal exponential mapping reveals useful imageprocessing.properties. ...
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A picture digitization grid based on logarithmic spirals rather than Cartesian coordinates is presented. Expressing this curvilinear grid as a conformal exponential mapping reveals useful imageprocessing.properties. The mapping induces a computational simplification that suggests parallel architectures in which most geometric transformations are effected by data shifting in memory rather than arithmetic on coordinates. These include fast, parallel noise-free rotation, scaling, and some projective transformations of pixel defined images. Conformality of the mapping preserves local picture-processing.operations such as edge detection.
A description is given of a versatile imageprocessing.system developed at Pratt & Whitney Aircraft (P&WA) and the highly efficient spatial domain filtering techniques which are its computational heart. By exp...
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A description is given of a versatile imageprocessing.system developed at Pratt & Whitney Aircraft (P&WA) and the highly efficient spatial domain filtering techniques which are its computational heart. By exploiting block average filtering techniques requiring only local storage, each block filtering operation uses only four additions and one multiplication per pixel, regardless of image or block size. As a consequence, extremely rapid imageprocessing.is possible; for example, deconvolution of a 512 multiplied by 512 pixel image can be performed in just five seconds on an IBM 3033 with Fortran code.
A recursive algorithm is given to directly compute the fast Fourier Transform (FFT) of a two-dimensional image array. The algorithm builds the FFT of a 2**m by 2**m matrix left bracket f right bracket by first mapping...
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A recursive algorithm is given to directly compute the fast Fourier Transform (FFT) of a two-dimensional image array. The algorithm builds the FFT of a 2**m by 2**m matrix left bracket f right bracket by first mapping its entries to form a new matrix left bracket f//1 right bracket , in a manner analogous to that used in one-dimensional FFT's. The FT of left bracket f right bracket is then found by computing the FT of all 2 by 2 submatrices of left bracket f//1 right bracket and recursively combining them into higher level submatrices until the 2**m by 2**m level is reached. This algorithm is shown to be computationally faster than the conventional method based on one-dimensional FFT's. The main features of this method, however, are its simplicity of updating the FFT of an image array when some of the array elements have been modified, and its suitability for implementation on a multiprocessor computer system. Applications of this algorithm to imageprocessing.are discussed and illustrative examples are given.
It is shown that the Hough transform may be used for encoding of line curves and waveforms that consist of the concatenation of curves from an underlying set of families of curves. Several properties of the transform ...
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It is shown that the Hough transform may be used for encoding of line curves and waveforms that consist of the concatenation of curves from an underlying set of families of curves. Several properties of the transform are given in this context.
A description is provided of a particular Computed Radiography system as it evolved from a Computed Tomography system. A comparison of image performance is made between this system and standard film screen radiography...
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A description is provided of a particular Computed Radiography system as it evolved from a Computed Tomography system. A comparison of image performance is made between this system and standard film screen radiography. Some of the imageprocessing.techniques used to construct and enhance the radiographic images are described.
When any edge detection technique is applied to a picture, the resulting edge image will contain noise, cracks, and parasitic branches. To remove these, an algorithm was designed which grows local trees along the boun...
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When any edge detection technique is applied to a picture, the resulting edge image will contain noise, cracks, and parasitic branches. To remove these, an algorithm was designed which grows local trees along the boundary and prunes these trees to provide linear and clean contours for objects in the picture.
A method for optimizing the performance of the line detector described by Duda and Hart is presented. Comparisons are made of the error probabilities for the optimal and previous schemes. A method for approximating th...
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A method for optimizing the performance of the line detector described by Duda and Hart is presented. Comparisons are made of the error probabilities for the optimal and previous schemes. A method for approximating the optimal scheme is also presented.
A discussion is presented of a facet model for image data which has the potential for fitting the form of the real idealized image, and for describing how the observed image differs from the idealized form. It is also...
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A discussion is presented of a facet model for image data which has the potential for fitting the form of the real idealized image, and for describing how the observed image differs from the idealized form. It is also an appropriate form for a variety of imageprocessing.algorithms. Then the authors give a relaxation procedure, and prove its convergence, for determining an estimate of the ideal image from observed image data.
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