We exploit the relationship between a general Gibbs random field and a mutually compatible Gibbs random field image, we investigate the possibility of approximating a general Gibbs random field by a mutually compatibl...
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We exploit the relationship between a general Gibbs random field and a mutually compatible Gibbs random field image, we investigate the possibility of approximating a general Gibbs random field by a mutually compatible Gibbs random field, and we study the consequences of such an approximation. This study is important, since, in some cases, various problems related to the modeling of images via Gibbs random fields may be simplified by restricting our interest to a special and convenient class of Gibbs random fields, the class of mutually compatible Gibbs random fields. A general analysis is presented, which results in some interesting conclusions about the desired relationship. We consider two approaches to the approximation problem. The first approach, which is more accurate, can be easily applied to the case of binary images. For nonbinary images this approach becomes cumbersome, since it requires the solution of a large system of nonlinear equations. The second approach, which is simpler but less accurate, is based on the direct relationship between the parameters of a general Gibbs random field and the parameters of a mutually compatible Gibbs random field. Simulation examples demonstrate various aspects of our analysis.
This paper describes an approach of feature extraction from range and intensity data for three-dimensional model-based target recognition systems. The range image of the object under study is acquired using a methodol...
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The authors present a new Monte Carlo simulation technique for the estimation of the partition function of a general Markov random field (MRF), which results in unbiased, consistent and asymptotically efficient estima...
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The authors present a new Monte Carlo simulation technique for the estimation of the partition function of a general Markov random field (MRF), which results in unbiased, consistent and asymptotically efficient estimates. This technique gives extremely accurate results, as demonstrated by simulations. Use of more efficient algorithms can boost the performance and accuracy of the method, and yield more reliable estimates.< >
An algorithm for detecting neural processes in serial optical sections for use in an automated three-dimensional neural reconstruction system is presented. This parsimonious, nonlinear, psychophysically motivated algo...
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An algorithm for detecting neural processes in serial optical sections for use in an automated three-dimensional neural reconstruction system is presented. This parsimonious, nonlinear, psychophysically motivated algorithm addresses the problems specific to neural element detection and localization, viz., images with minimal resolution, operators with small spatial supports, highly curved, filamentous features, large variation in feature intensity profile, poor signal-to-noise ratio, and determination of depth without stereo. One first finds the magnitude and orientation of the maximum intensity second directional derivative. A family of curves is locally fitted to these data, and the projections of the data on the curve family are found. If a pixel lies on a curve with sufficient total projection, it is labeled with the magnitude, orientation, curvature, spatial extent, and element displacement. Depth is interpolated from the spatial extent data for corresponding neighborhoods in three adjacent (in depth) images by using an approximation to the depth-dependent optical point spread function. Experimental results using photomicrographs of cat visual cortex are presented.< >
The authors develop a path metric for sequential search based on the linear model. The metric forms the heart of an edge-linking algorithm that combines edge elements enhanced by an optimal filter. From a starting nod...
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The authors develop a path metric for sequential search based on the linear model. The metric forms the heart of an edge-linking algorithm that combines edge elements enhanced by an optimal filter. From a starting node, transitions are made to the goal nodes by a maximum likelihood metric. This metric requires only local calculations on the search space and its use in edge linking provides more accurate results than other linking techniques.< >
A method to reconstruct motion from sequences of tagged magnetic resonance (MR) images is presented. MR tagging is used to create a spatial pattern of varying magnetization so that objects which may otherwise have con...
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A method to reconstruct motion from sequences of tagged magnetic resonance (MR) images is presented. MR tagging is used to create a spatial pattern of varying magnetization so that objects which may otherwise have constant intensity are textured; this reduces the motion ambiguity associated with the aperture problem in computervision. To account for the decay of the tag pattern, a new optical flow algorithm is developed and implemented. Velocity fields estimated using this algorithm are used to recursively update the implied motion reference map over time, thereby tracking the motion of individual particles. If a segmentation of the object is known at the time the tag pattern is created, then an object may be selectively tracked, using the estimated reference map to update the object's position as time progresses. Results are shown for actual MR phantom data.< >
The image reconstruction capacity of the actual foveal cone sampling mosaics of an adult monkey and human is investigated through computer simulations. A retinocortical mapping model in which positions are known and d...
A general theory for the morphological representation of discrete and binary images is presented. Particular cases of the general scheme are shown to yield a number of useful image representations. The effect of noise...
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A general theory for the morphological representation of discrete and binary images is presented. Particular cases of the general scheme are shown to yield a number of useful image representations. The effect of noise degradation is studied. It is proven that, under certain assumptions, the general reduced morphological skeleton is the best morphological representation among a collection of invertible morphological image representations. This representation results in a minimal upper-bound on the average probability of error of reconstructing a binary image from its noisy representation.< >
A projection-space approach for reconstruction from projections is presented. This approach uses the known convex support of the object both as a penalty term in a variational problem defined in projection-space and a...
A projection-space approach for reconstruction from projections is presented. This approach uses the known convex support of the object both as a penalty term in a variational problem defined in projection-space and as a guide to the specification of optimal smoothing coefficients that may vary spatially. Partial consistency of the sinogram is provided by including mass and center-of-mass constraints in the variational formulation. An outline of the general approach and calculations for a specific example are provided. computer simulations are provided for evaluation of the performance in this special case
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