The authors define point symmetry for convex digital regions. They restrict their attention to convex digital regions that are N-connected. An efficient algorithm is presented to determine the points of symmetry of su...
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ISBN:
(纸本)0818608625
The authors define point symmetry for convex digital regions. They restrict their attention to convex digital regions that are N-connected. An efficient algorithm is presented to determine the points of symmetry of such regions by eliminating portions of a feasible region. If a convex digital region is not N-connected, the main result still applies and algorithm can still be used after some modifications. However, point symmetry for convex digital regions that are not N-connected may not be meaningful.
A high level imageprocessing language is discussed that provides a robust environment for the universal specification and implementation of imageprocessing algorithms. In essence, an imageprocessing program consist...
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ISBN:
(纸本)0818608625
A high level imageprocessing language is discussed that provides a robust environment for the universal specification and implementation of imageprocessing algorithms. In essence, an imageprocessing program consists of a collection of procedure calls. To implement an algorithm, one need only construct a block-diagram representation of the algorithm and then proceed with the one-to-one translation of the block diagram into the host PASCAL language. The result is that an investigator can proceed with rapid variations at the algorithm design stage without having to be involved with writing code. The development of the language rests on three pillars: (1) the existence of a rigorous and robust image algebra, (2) the block diagram specification of image-processing algorithms, and (3) the bound matrix image representation.
A vectorization method for line patterns is proposed which converts digital binary images into line segment vectors. The vector data is more compact and more natural than that obtained by conventional methods using th...
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ISBN:
(纸本)0818608625
A vectorization method for line patterns is proposed which converts digital binary images into line segment vectors. The vector data is more compact and more natural than that obtained by conventional methods using thinning operations. The proposed method consists of four steps. First, thinning of an input binary image is performed. Then a medial line image obtained by the thinning operation is transformed into a graph, in which pixels on the medial line correspond to nodes and neighboring nodes are connected by edges. Next, extra edges unnecessary for preserving the topology of the medial line image are deleted. The deletion can be implemented as an iterative parallel operation. Finally, the graph is simplified by line approximation. Every step except the line approximation is suitable for parallel processing. The experimental results of applying the proposed method to geographical maps show that the method reduces data volume by about 30%, as compared with conventional methods.
The VISIONS Schema System provides a framework for building a general interpretation system as a distributed network of many small special-purpose interpretation systems. Each schema is an 'expert' at recogniz...
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ISBN:
(纸本)0818608625
The VISIONS Schema System provides a framework for building a general interpretation system as a distributed network of many small special-purpose interpretation systems. Each schema is an 'expert' at recognizing one type of object. A discussion is presented of the problems of knowledge representation in a distributed AI environments and the Schema System's approach to those problems. A series of interpretation experiments have been performed on nine images from two natural scene domains;results from three images are presented.
The authors provide theoretical justification for the use of zero crossings of residuals (between a filtered image and the original) for edge detection. The smoothed version is obtained by bilinear interpolation as a ...
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ISBN:
(纸本)0818608625
The authors provide theoretical justification for the use of zero crossings of residuals (between a filtered image and the original) for edge detection. The smoothed version is obtained by bilinear interpolation as a result of two-dimensional discrete regularization of subsampled images. The method is also applicable to smoothed images obtained by convolution with a Gaussian. Examples of applications of the method are shown for three kinds of pictures: aerial photographs, low-quality pictures of tools, and a high-quality picture of a face. The same parameters are used in all the examples. In addition they show examples of the results of one of the Canny edge detectors on the same pictures.
A uniform hierarchical procedure for processing incomplete image data is described. It begins with the computation of local moments within windows centered on each output sample point. Arrays of such measures, called ...
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ISBN:
(纸本)0818608625
A uniform hierarchical procedure for processing incomplete image data is described. It begins with the computation of local moments within windows centered on each output sample point. Arrays of such measures, called moment images, are computed efficiently through the application of a series of small kernel filters. A polynomial surface is then fit to the available image data within a local neighborhood of each sample point. Best-fit polynomials are obtained from the corresponding local moments. The procedure, hierarchical polynomial fit filtering, yields a multiresolution set of low-pass-filtered images. The set of low-pass images is combined by multiresolution interpolation to form a smooth surface passing through the original image data.
The previous implementations of the authors' epipolar-plane image-analysis mapping technique demonstrated the feasibility and benefits of the approach, but were carried out for restricted camera geometries. The qu...
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ISBN:
(纸本)0818608625
The previous implementations of the authors' epipolar-plane image-analysis mapping technique demonstrated the feasibility and benefits of the approach, but were carried out for restricted camera geometries. The question of more general geometries made the technique's utility for autonomous navigation uncertain. The authors have developed a generalization of the analysis that (a) enables varying view direction, including varying over time;(b) provides three-dimensional connectivity information for building coherent spatial descriptions of observed objects, and (c) operates sequentially, allowing initiation and refinement of scene feature estimates while the sensor is in motion. To implement this generalization it was necessary to develop an explicit description of the evolution of images over time. They achieved this by building a process that creates a set of two-dimensional manifolds defined at the zeros of a three-dimensional spatiotemporal Laplacian. These manifolds represent explicitly both the spatial and temporal structure of the temporally evolving imagery and are termed spatiotemporal surfaces.
A description is given of a knowledge-based vision system for recognizing and classifying man-made objects in aerial images. images are interpreted and image object descriptors are created, based on model-driven high-...
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ISBN:
(纸本)0818608625
A description is given of a knowledge-based vision system for recognizing and classifying man-made objects in aerial images. images are interpreted and image object descriptors are created, based on model-driven high-level vision processing. Knowledge of various low-level vision techniques, and their applicability to generic applications are used to dynamically select specific low-level vision techniques for image segmentation. Terrain map and feature information is used as an adjunct by the low-level vision to assist in image segmentation, and by high-level vision for image interpretation. The authors have used a unique software architecture based on standard knowledge-based approaches in which knowledge is represented explicitly and is separated from program control. Off-the-shelf tools including Lisp and the ART language from Inference corporation, running on a Symbolics 3675, were used. The current system has been tested both with low-resolution forward-looking infrared (FLIR) images for target cueing and higher-resolution airport scenes for scene analysis.
The authors introduce a novel pixel-based (iconic) algorithm that estimates depth and depth uncertainty at each pixel and incrementally refines these estimates over time. They describe the algorithm for translations p...
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ISBN:
(纸本)0818608625
The authors introduce a novel pixel-based (iconic) algorithm that estimates depth and depth uncertainty at each pixel and incrementally refines these estimates over time. They describe the algorithm for translations parallel to the image plane and contrast its formulation and performance to that of a feature-based Kalman filtering algorithm. They compare the performance of the two approaches by analyzing their theoretical convergence rates, by conducting quantitative experiments with images of a flat poster, and by conducting qualitative experiments with images of a realistic outdoor scene model. The results show that the method is an effective way to extract depth from lateral camera translations and suggest that it will play an important role in low-level vision.
Morphological operations are used for segmentation, feature generation, and location extraction. A recursive adaptive thresholding algorithm transforms a gray-level image into a set of multiple level regions of object...
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ISBN:
(纸本)0818608625
Morphological operations are used for segmentation, feature generation, and location extraction. A recursive adaptive thresholding algorithm transforms a gray-level image into a set of multiple level regions of objects. A distance transformation algorithm then is used to transform a binary image into the minimum distance from each object point to the object's boundary. This algorithm uses a morphological erosion with a large structuring element which may correspond to Euclidean, city-block, or chessboard distance measures. For rotation-invariance and precision measurements, the Euclidean distance should be chosen. The large Euclidean structuring element can be decomposed into the maximum of recursive dilations with multiple small structuring components, which allows the easy implementation of this algorithm. A shape library database with hierarchical features is automatically generated. The features extracted are the shape number and the skeletal local-maximum points radii and coordinates. Object recognition is achieved by comparing the shape number and the hierarchical radii. Object location is detected by a hierarchical morphological bandpass filter.
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