The growing use and analysis of images by computer presents many problems in managing images and image information. Solutions to these problems can be specific, with file structures to represent the needed information...
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The growing use and analysis of images by computer presents many problems in managing images and image information. Solutions to these problems can be specific, with file structures to represent the needed information, or general, such as a general Data Base Management System. A presentation is made of a compromise solution, a Raster image File Format (RIFF), that uses image file headers for the storage of specific image format information, as well as very general Name-Value pair information. This latter structure enables varying kinds of information to be represented, including links to other kinds of image data structures as the need arises.
Modern scanning techniques, such as computed tomography, have begun to produce true three-dimensional imagery of internal structures. The first stage in finding structure in these images, like that for standard two-di...
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Modern scanning techniques, such as computed tomography, have begun to produce true three-dimensional imagery of internal structures. The first stage in finding structure in these images, like that for standard two-dimensional images, is to evaluate a local edge operator over the image. If an edge segment in two-dimensions is modelled as an oriented unit line segment that separates unit squares (i. e. , pixels) of different intensities, then a three-dimensional edge segment is an oriented unit plane that separates unit volumes (i. e. , voxels) of different intensities. In this study the authors derive an operator that finds the best oriented plane at each point in the image. This operator, which is based directly on the 3-D problem, complements other approaches that are either interactive or heuristic extensions of 2-D techniques.
A description is given of a general automatic, region based image segmentation technique. This technique is based on a simple thresholding procedure applied recursively to obtain a complete segmentation. The results o...
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A description is given of a general automatic, region based image segmentation technique. This technique is based on a simple thresholding procedure applied recursively to obtain a complete segmentation. The results on the test image are presented and discussed.
Object location in computed tomography images is a preliminary step required for many automated measurements which may be useful in many diagnostic procedures. Most object location, imageprocessing techniques are eit...
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Object location in computed tomography images is a preliminary step required for many automated measurements which may be useful in many diagnostic procedures. Most object location, imageprocessing techniques are either globally based such as histogram segmentation or locally based such as edge detection. The method described uses both local and global information for object location. The technique has been applied to the location of suspected tumors in CT lung and brain images. Sorting and merging steps are required for eliminating noise regions but all suspected tumor regions have been located. Measurements such as boundary roughness or density statistics may also be made on the objects and used to further identify suspicious regions for further study by the radiologists.
Objects are analyzed into generalized cylinders and relations between them. The class of cylinders used is restricted to straight-line axes (spines), elliptical cross-sections, and a sweeping rule whereby the lengths ...
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Objects are analyzed into generalized cylinders and relations between them. The class of cylinders used is restricted to straight-line axes (spines), elliptical cross-sections, and a sweeping rule whereby the lengths of the major and minor axes of the ellipses change linearly and independently. Most smooth elongated objects can be described as compositions of such cylinder primitives. Descriptions can be compared to each other and to object prototypes. Two algorithms are developed and tested for extracting cylinder descriptions from stacks of parallel slices. A local algorithm creates cylinders from elliptical regions on adjacent slices. A predictive algorithm hypothesises cylinders from regions on non-adjacent slices and then tests the hypotheses by intelligently requesting intermediate slices. Both algorithms explain complex non-elliptical regions (joints, typically) by using cylinders impinging upon them as keys to their shapes.
The problem of texture discrimination is considered. Random walks are performed in a plane domain D bounded by an absorbing boundary GAMMA , and the absorption distribution is calculated. Measurements derived from suc...
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The problem of texture discrimination is considered. Random walks are performed in a plane domain D bounded by an absorbing boundary GAMMA , and the absorption distribution is calculated. Measurements derived from such distributions are the features used for discrimination. Experiments using the model are performed and results are shown.
In routine examination of chest radiographs, radiologists miss about 30% of the lung tumors in these pictures. To aid the radiologist in detecting these tumors the authors have designed and constructed, and are contin...
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In routine examination of chest radiographs, radiologists miss about 30% of the lung tumors in these pictures. To aid the radiologist in detecting these tumors the authors have designed and constructed, and are continuing to develop, a system consisting of a scanning microdensitometer, a digital minicomputer, a computer program, and a digital cathode-ray-tube color display. This system detects nodules in the range 5mm to 25mm mm and classifies them into two classes: tumor and nontumor. On a data base of 14 nodules in five radiographs, our system missed only one nodule and produced an average of seven false positives per radiograph.
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.
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.
Several graphic techniques are presented which are useful for evaluating certain types of clustering algorithms. Some of the techniques require only a plotter, while others require interactive graphics capabilities. T...
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Several graphic techniques are presented which are useful for evaluating certain types of clustering algorithms. Some of the techniques require only a plotter, while others require interactive graphics capabilities. The techniques are illustrated using three different clustering algorithms and four different data sets.
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