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 method to reduce image resolution that simulates the reduction of shape resolution is presented. Such resolution reduction is critical for shape-from-shading algorithms. This method of resolution reduction is used i...
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ISBN:
(纸本)081861952x
A method to reduce image resolution that simulates the reduction of shape resolution is presented. Such resolution reduction is critical for shape-from-shading algorithms. This method of resolution reduction is used in accelerating the shape from shading by using small multiresolution pyramids. A Lambertian reflectance model is used, but a similar approach can be developed for other reflectance models. The goal is to show that the resolution reduction based only on image intensities is inferior to resolution reduction using knowledge on the surface reflectance.
The problem considered here involves the use of a sequence of monocular images of a three-dimensional moving object to estimate both its structure and kinematics. The object is assumed to be rigid, and its motion is a...
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The problem considered here involves the use of a sequence of monocular images of a three-dimensional moving object to estimate both its structure and kinematics. The object is assumed to be rigid, and its motion is assumed to be smooth. A set of object match points is assumed to be available, consisting of fixed features on the object, the image plane coordinates of which have been extracted from successive images in the sequence. The measured data are the noisy image plane coordinates of this set of object match points, taken from each image in the sequence. In previous papers [ieee Trans. pattern Anal. Mach. Intell. PAMI-8 , 90 (1986); in proceedings of the ieee Workshop on Motion: Representation and Analysis (Institute of Electrical and Electronics Engineers, New York, 1986), p. 95; in proceedings of the ieeeconference on computer Vision and patternrecognition (Institute of Electrical and Electronics Engineers, New York, 1986), p. 176] we discussed model-based approaches for motion and structure estimation from a long sequence of images. We examine here the performance of such techniques by using a Cramér–Rao lower bounds on the estimation error variance. This method permits a priori prediction of estimation accuracy as a function of a number of factors, including the number of images in the sequence, the time at which each image is made, the number of feature points used, the image-plane noise level, and the type of motion that is involved. Theoretical performance predictions are compared with the statistics of Monte Carlo simulation, and it is shown that the actual estimation accuracy is close to the Cramér–Rao bounds in most cases. These results also show that noisy sequences with fewer than four images often do not contain enough information to permit accurate estimation of motion and structure parameters. This conclusion is consistent with the observed instability of so-called two-frame estimation methods in the presence of noise.
The authors report theoretical and experimental results which underline the importance of mutual illumination to visual modules dealing with shape and with surface lightness. The experiments are in good agreement with...
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ISBN:
(纸本)081861952x
The authors report theoretical and experimental results which underline the importance of mutual illumination to visual modules dealing with shape and with surface lightness. The experiments are in good agreement with results obtained with a simple theoretical model. These results show the effects of mutual illumination in pictures of simple objects, and indicate that these effects must be accounted for in modeling image intensities. The data imply that shape from shading based on the image irradiance equation make real errors on images of concave objects, and that edge detectors that respond to only step edges perform badly on polyhedral scenes and waste information.
It has been shown by A. L. Yuille and T. Poggio (1983) that the scale-space image of a signal determines that signal uniquely up to constant scaling. Here, generalization of the proof given by Yuille and Poggio is pre...
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ISBN:
(纸本)081861952x
It has been shown by A. L. Yuille and T. Poggio (1983) that the scale-space image of a signal determines that signal uniquely up to constant scaling. Here, generalization of the proof given by Yuille and Poggio is presented. It is shown that the curvature scale-space image of a planar curvature determines the curvature uniquely, up to constant scaling and a rigid motion. The results show that a 1-D signal can be reconstructed using only one point from its scale-space image. This is an improvement of the result obtained by Yuille and Poggio.
A technique is presented which utilizes the polarization properties of reflected light to separate specular and diffuse components of reflection. This technique works for both dielectric and metal surfaces, regardless...
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ISBN:
(纸本)081861952x
A technique is presented which utilizes the polarization properties of reflected light to separate specular and diffuse components of reflection. This technique works for both dielectric and metal surfaces, regardless of the color of the illuminating light source or the color detail on the object surface. In addition to separating out diffuse and specular components of reflection, the technique can also identify whether certain image regions correspond to a dielectric or metal object surface. Extensive experimentation is presented for a variety of dielectric and metal surfaces, both polished and rough, using a point light source.
A standard probabilistic formulation of a local shape estimator due to Witkin (1980) has been demonstrated to work to some extent on a range of data, but it also has been shown to overestimate slant. Here, the author ...
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ISBN:
(纸本)081861952x
A standard probabilistic formulation of a local shape estimator due to Witkin (1980) has been demonstrated to work to some extent on a range of data, but it also has been shown to overestimate slant. Here, the author identifies and analyzes three sources of this error: the choice of prior probability distribution on shape;as systematic bias in the observation of image events;and a kind of nonergodicity in the stochastic process associated with surface events. As a result of this analysis, the author formulates a corrected probabilistic local shape estimator, proves a correctness theorem for it, and demonstrates its superiority to the Wilkin estimator in a set of experiments.
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.
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 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.
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