An edge detector is proposed which consists of a pair of a pattern and a linear filter. It is shown that for an edge in the input signal, there is a scaled pattern in the filter response. The location of the pattern i...
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ISBN:
(纸本)081861952x
An edge detector is proposed which consists of a pair of a pattern and a linear filter. It is shown that for an edge in the input signal, there is a scaled pattern in the filter response. The location of the pattern is the location of the edge, and the scaling factor of the pattern is the size of the edge. Therefore the problem of edge detection and measurement is reduced to searching for the (scaled) pattern in the filter response. In the presence of noise, the pattern matching is approximate. A statistical approach for the pattern search is proposed. Optimal detectors which minimize the effects of noise are studied;for white noise, the optimal detectors are natural splines. Testing results on real images are reported.
A technique for identifying the material properties of objects in an image using multiple images taken through a polarizing lens at various rotations in front of a stationary camera (only the filter moves). Using thes...
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ISBN:
(纸本)081861952x
A technique for identifying the material properties of objects in an image using multiple images taken through a polarizing lens at various rotations in front of a stationary camera (only the filter moves). Using these images, it is possible to obtain the classification of material surfaces at all points on a specular highlight. The algorithm is demonstrated on laboratory images. The authors assume a point source, the theory can only be applied at points where specular reflection dominates. Extensions of the theory to deal with extended light sources, which greatly increase the portion of the image giving rise to specular reflection, are also considered.
Segmentation using boundary finding is enhanced both by considering the boundary as a whole and by using model-based shape information. Flexible constraints, in the form of a probabilistic deformable model, are applie...
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ISBN:
(纸本)081861952x
Segmentation using boundary finding is enhanced both by considering the boundary as a whole and by using model-based shape information. Flexible constraints, in the form of a probabilistic deformable model, are applied to the problem of segmenting natural objects whose diversity and irregularity of shape makes them poorly represented in terms of fixed features of forms. The parametric model is based on the elliptic Fourier decomposition of the boundary. The segmentation problem is solved as an optimization problem, where the best match between the boundary (as defined by the parameter vector) and the image data is found. Initial experimentation shows good results on a variety of images.
A technique for the estimation of 2-D normal velocity is presented. The image sequence is first represented by a family of velocity-tuned linear filters. Normal velocity, in the individual filter outputs, is expressed...
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ISBN:
(纸本)081861952x
A technique for the estimation of 2-D normal velocity is presented. The image sequence is first represented by a family of velocity-tuned linear filters. Normal velocity, in the individual filter outputs, is expressed as the local first-order behavior of surfaces of constant phase. Justification for this is discussed, and it is shown to provide an effective basis for the local computation of normal velocity. The resultant approach is local in space-time. It permits multiple velocity estimates within a single neighborhood, and it yields accurate velocity estimates that are robust with respect to noise and perspective deformation.
A general theory for the morphological representation of discrete and binary images is presented. The theory relies on the generation of a set of nonoverlapping segments of an image by repeated erosions and set transf...
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ISBN:
(纸本)081861952x
A general theory for the morphological representation of discrete and binary images is presented. The theory relies on the generation of a set of nonoverlapping segments of an image by repeated erosions and set transformations, which in turn produces a decomposition that guarantees exact reconstruction. The morphological image-representation transform and its properties are examined, with focus on the relationship between the transform and some existing shape-analysis tools (e.g., discrete size transform, pattern spectrum), thus introducing the transform as the basis of a unified geometrical image analysis. Particular cases of the general representation scheme are shown to yield a number of useful image representations which are directly related to various forms of digital morphological skeletons. Also considered is the relationship between the transform and the various forms of morphological skeletons.
A method for parallel processing of chain-codable contours is described. The proposed hierarchical environment, called the chain pyramid, is similar to a regular nonoverlapping image pyramid structure. The chain pyram...
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ISBN:
(纸本)081861952x
A method for parallel processing of chain-codable contours is described. The proposed hierarchical environment, called the chain pyramid, is similar to a regular nonoverlapping image pyramid structure. The chain pyramid makes possible the fast computation of contours. The artifacts of contour processing on pyramids are eliminated by a probabilistic allocation algorithm. processing modules are developed for smoothing of curves, gap bridging in fragmented data, and treatment of branch points. Raw edge data are preprocessed before being input into the chain pyramid. Typical results are presented and briefly characterized.
A novel memory system is proposed for imageprocessing. Latin squares, which are well known combinatorial objects, are used as the skew function of the memory system. A Latin square with desired properties for image-a...
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ISBN:
(纸本)081861952x
A novel memory system is proposed for imageprocessing. Latin squares, which are well known combinatorial objects, are used as the skew function of the memory system. A Latin square with desired properties for image-array access is introduced. The resulting memory system provides access to various subsets of image data (rows, columns, diagonals, main subsquares, etc.) without memory conflict. The memory modules are fully utilized for most frequently used subsets of image data. The address generation can be performed in constant time. This memory system achieves constant-time access to rows, columns, diagonals, and subarrays using a minimum number of memory modules.
A method for detecting and describing the features of faces using deformable templates is described. The feature of interest, an eye for example, is described by a parameterized template. An energy function is defined...
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ISBN:
(纸本)081861952x
A method for detecting and describing the features of faces using deformable templates is described. The feature of interest, an eye for example, is described by a parameterized template. An energy function is defined which links edges, peaks, and valleys in the image intensity to corresponding properties of the template. The template then interacts dynamically with the image, by altering its parameter values to minimize the energy function, thereby deforming itself to find the best fit. The final parameter values can be used as descriptors for the features. This method is demonstrated by showing deformable templates detecting eyes and mouths in real images.
An efficient method for finding straight lines in edge maps is described. The algorithm is based on a pyramid structure. At the bottom level of the pyramid, short line segments are detected by applying a Hough transfo...
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ISBN:
(纸本)081861952x
An efficient method for finding straight lines in edge maps is described. The algorithm is based on a pyramid structure. At the bottom level of the pyramid, short line segments are detected by applying a Hough transform to small subimages. The algorithm proceeds, bottom up, from this low-level description by grouping line segments within the local neighborhoods into longer lines. Line segments which have local support propagate up the hierarchy and take part in grouping at higher levels. The length of a line determines approximately the level in the pyramid to which it propagates, and a hierarchical description of the line segments in a scene is obtained. The line-segment-grouping process is also based on a Hough transform. The method is quite efficient and has an attractive architecture which is suitable for parallel implementation.
The use of Markov random fields (MRFs) in color image segmentation of natural outdoor scenes is discussed. MRFs provide an elegant means of specifying a local energy function which embodies the expected dependencies o...
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ISBN:
(纸本)081861952x
The use of Markov random fields (MRFs) in color image segmentation of natural outdoor scenes is discussed. MRFs provide an elegant means of specifying a local energy function which embodies the expected dependencies of neighboring pixels and includes both the prior and posterior probabilistic distributions. This local neighborhood-based specification of dependencies avoids ad hoc brittle methods using global image knowledge. A brief analysis of ongoing research in color differencing methods is presented, since they are central to the problem of color segmentation. The authors develop and compare the use of three different lattice structures for coupled MRFs with line and color processes based on squares, hexagons, and triangles, and also discusses current efforts in MRF parameter understanding.
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