A description is provided of some novel algorithms for patternrecognition research and a framework for efficient development, maintenance, and sharing of interactive software among several users and diverse applicati...
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A description is provided of some novel algorithms for patternrecognition research and a framework for efficient development, maintenance, and sharing of interactive software among several users and diverse application areas. This modular interactive software system (MISS) forms the basis of a general purpose image analysis and patternrecognition research system (IPS). The algorithms and some preliminary results are discussed first. Then, the MISS and IPS software systems are described.
The three-dimensional shape analysis problem is a very demanding test of shape analysis algorithms. Previous approaches to the problem have employed global features such as moments and Fourier descriptors. Global feat...
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The three-dimensional shape analysis problem is a very demanding test of shape analysis algorithms. Previous approaches to the problem have employed global features such as moments and Fourier descriptors. Global features lack the capacity for solving the partial shape recognition problem, in which only part of the unknown shape is available. Previous approaches to local shape analysis have employed structural (syntactic) methods, but these methods have so far failed to solve the three-dimensional problem. This study describes a hybrid structural/statistical local shape analysis algorithm which is applied to the three-dimensional problem.
An analysis is given of the Moire pattern formation in scanning and reproducing halftone pictures. The analysis includes the effects of the aperture size and shape of the reproduction printing process. Also the effect...
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An analysis is given of the Moire pattern formation in scanning and reproducing halftone pictures. The analysis includes the effects of the aperture size and shape of the reproduction printing process. Also the effects of parallelogram grid sampling as well as square grid sampling have been taken into consideration. A simulation program has been written to synthesize the Moire patterns based upon the Fourier transform of the output picture. Several observations will be discussed and among two of the more important ones are: (a) Moire fringes can result from beating together of clusters of Fourier spatial frequencies and (b) fixed value thresholding intensifies Moire patterns.
In dynamic radiological studies time-dependent processes, ranging from motion of the patient's own anatomical structures to the kinetics of a contrast agent or radiotracer, are recorded in a sequence of image fram...
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In dynamic radiological studies time-dependent processes, ranging from motion of the patient's own anatomical structures to the kinetics of a contrast agent or radiotracer, are recorded in a sequence of image frames. If the data are available in digital format, appreciation of regional patterns of behavior can be enhanced by digital operations on the image sequence. These operations can be considered as projecting out aspects of temporal behavior that are not readily or unambiguously perceptible to the unassisted observer. A report is presented on experiences with such functional images in three radiological modalities at the University of Wisconsin. Examples include nuclear medicine studies of the heart and liver, transmission computed tomography studies of the brain, and digital fluoroscopic studies of the heart and kidneys.
A study was conducted to evaluate the usefulness of equal probability quantization as a preprocessing.step in the automated interpretation of chest radiographs for pneumoconiosis. Nineteen chest radiograph pairs were ...
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A study was conducted to evaluate the usefulness of equal probability quantization as a preprocessing.step in the automated interpretation of chest radiographs for pneumoconiosis. Nineteen chest radiograph pairs were analyzed. Each pair of radiographs consisted of a good quality film and a duplicate film on the same miner of acceptable but slightly poorer quality, as judged by two radiologists. The results of the study suggests that some reduction in the within subject variability of horizontal texture measurements can be obtained by preprocessing.of the radiographs with equal probability quantization. This preprocessing.step reduces the dependency of the texture measurements on film quality, although whether a corresponding improvement in classification accuracy can be obtained remains to be proven.
The problem of automatic registration of deformed images is addressed. It describes an iterative technique for gradually updating the local registration of two images based on a dynamic cooperative model. the method i...
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The problem of automatic registration of deformed images is addressed. It describes an iterative technique for gradually updating the local registration of two images based on a dynamic cooperative model. the method is cooperative in the sense that a feature at one location in an image influences decisions made at other locations. Initially, when registration is expected to be poor and feature measures unreliable, cooperative interaction is strong. It is progressively weakened with each iteration to permit matching of fine details. For a physical analogy, consider an elastic picture whose stiffness decreases with each iteration, and which is deformed by forces arising from similar features in another picture. Examples are shown for both dot patterns and gray-scale pictures.
The shape of a two-dimensional contour can be conveniently transformed into an amplitude-vs-distance signal by allowing a line segment of specified length to trace out the contour and recording the angular variation o...
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The shape of a two-dimensional contour can be conveniently transformed into an amplitude-vs-distance signal by allowing a line segment of specified length to trace out the contour and recording the angular variation of the line segment as a function of distance along the contour. The line segment, which connects two points on the contour, may be of strictly fixed length or may span a fixed number of links in a chain-coded representation of the contour. The contour may be closed or open. The record of angular variation (i. e. , the incremental curvature) is independent of the orientation of the contour and can also be made independent of scale.
image data compression can be achieved by a number of techniques such as DPCM and Transform Coding. Adaptive image compression can be done with any of these techniques. Adaptive image data compression is a procedure i...
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image data compression can be achieved by a number of techniques such as DPCM and Transform Coding. Adaptive image compression can be done with any of these techniques. Adaptive image data compression is a procedure in which the number of bits allocated to each image block changes from block to block depending on the block complexity. This variable input bit rate must be converted to a constant output bit rate by a rate buffer. A study is made of some causal and noncausal approaches to adaptively allocating bits under the constraint of a fixed size buffer. A discussion is also presented of the optimal noncausal approach whose performance is a least upper bound on any causal approach.
An algorithm for finding the medial axis of an object in a 2-D binary picture has been developed. A set of real-valued boundary points for the object is extracted and smoothed using a linear combination of points in t...
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An algorithm for finding the medial axis of an object in a 2-D binary picture has been developed. A set of real-valued boundary points for the object is extracted and smoothed using a linear combination of points in the immediate neighborhood. A more detailed set of points is then defined by interpolation using a parabolic blending technique. To obtain the medial axis, circles are fitted for each point in the detailed set of points. Ech circle must be tangent to the point, be totally enclosed by the object and be of maximum size. The centers of these circles lie on the medial axis. The technique is especially suited to noisy data or coarsely sampled shapes.
Two means for numerically evaluating edge detectors, relative and absolute grading, were developed. Relative grading involves comparing an edge operator's output to the concensus decision of other operators. Absol...
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Two means for numerically evaluating edge detectors, relative and absolute grading, were developed. Relative grading involves comparing an edge operator's output to the concensus decision of other operators. Absolute grading compares any operator to a manually constructed key or target scene. A test of the ability of these techniques to eliminate operator and thresholding noise, improve threshold levels, system parameters and to guide operator improvement was carried out on six operators: Sobel, Robert's gradient, Roberts' square root gradient, gradient, range and Frei-Chen.
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