We describe a novel Bayesian approach to region merging, which directly uses statistical image models to determine the probability that the union of two regions is homogeneous, and does not require parameter estimatio...
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ISBN:
(纸本)0818638826
We describe a novel Bayesian approach to region merging, which directly uses statistical image models to determine the probability that the union of two regions is homogeneous, and does not require parameter estimation. This approach is particularly beneficial for cases in which the merging decision is most likely to be incorrect: when little information is contained in one or both of the regions and parameter estimates are unreliable. We apply the formulation to the implicit polynomial surface model for range data and texture models for intensity images.
This paper deals with the development of an efficient model based approach to detect and characterize precisely important features such as edges, corners and vertices. The key of our approach is first to propose some ...
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ISBN:
(纸本)081863880X
This paper deals with the development of an efficient model based approach to detect and characterize precisely important features such as edges, corners and vertices. The key of our approach is first to propose some efficient models associated to each of these features and second, to efficiently extract and characterize these features directly from the image by searching the parameters of the model that best approximate the observed grey level image intensities. Due to the large amount of time required by a first approach that assumes the blur of the imaging acquisition system to be describable by a 2D Gaussian filter, different solutions that drastically reduce this computational time are considered and developed in this paper. The important problem of the initialization phase in the minimization process is also considered and an original and efficient solution is proposed. A large number of experiments involving real images have been carried out in order to test and compare the reliability, the robustness and the efficiency of the different proposed approaches.
Due to the aperture problem, the only general unambiguous motion measurement in images is normal flow-the projection of image motion on the gradient direction. In this paper we show how a monocular observer can estima...
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ISBN:
(纸本)081863880X
Due to the aperture problem, the only general unambiguous motion measurement in images is normal flow-the projection of image motion on the gradient direction. In this paper we show how a monocular observer can estimate its 3D motion relative to the scene us using normal flow measurements in a global and qualitative way. It is proved that local normal flow measurements form global patterns in the image plane. The position of these patterns is related to the three dimensional motion parameters. By locating some of these patterns, which depend only on subsets of the motion parameters, through a simple search technique, the 3D motion parameters can be found. The proposed algorithmic procedure is very robust, since it is not affected by small perturbations in the normal flow measurements. As a matter of fact, since only the sign of the normal flow measurement is employed, the direction of translation and the axis of rotation can be estimated with up to 100 percent error in the image measurements.
We attempt to solve the problem of imperfect data produced by state-of-the-art edge detectors through the implementation of laws of Perceptual Grouping, derived from the psychology field. We introduce a saliency-enhan...
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ISBN:
(纸本)081863880X
We attempt to solve the problem of imperfect data produced by state-of-the-art edge detectors through the implementation of laws of Perceptual Grouping, derived from the psychology field. We introduce a saliency-enhancing operator capable of highlighting features (edges, junctions etc.) which are considered `important' psychologically. It also infers features which are not detected by low-level detectors. We show how to extract salient curves and junctions and generate a description ranking these features by the likelihood of them occurring accidentally. We also treat the problems of illusory contours apparent in end-point formations. The scheme is particularly useful as a gap filter and in the presence of a large amount of noise. It is interesting to note that all operations are parameter-free, non-iterative and are linear with the number of edges in the input image.
We describe an analytical method for recovering 3-D motion and structure of four or more points from one motion of a stereo rig. The extrinsic parameters are unknown. The motion of the stereo rig is also unknown. Beca...
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ISBN:
(纸本)0818638826
We describe an analytical method for recovering 3-D motion and structure of four or more points from one motion of a stereo rig. The extrinsic parameters are unknown. The motion of the stereo rig is also unknown. Because of the exploitation of information redundancy, the approach gains over the traditional `motion and structure from motion' approach in that less features and less motions are required, and thus more robust estimation of motion and structure can be obtained. Since the constraint on the rotation matrix is not fully exploited in the analytical method, nonlinear minimization can be used to improve the result. Both computer simulated data and real data are used to validate the proposed algorithm, and very promising results are obtained.
We address ground state (energy-minimizing) texture patterns in Markov random field (MRF) image models specifically, the second-order Ising model. Ground state texture patterns are obtained for arbitrary parameter val...
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ISBN:
(纸本)0818638826
We address ground state (energy-minimizing) texture patterns in Markov random field (MRF) image models specifically, the second-order Ising model. Ground state texture patterns are obtained for arbitrary parameter values. A small number of texture classes can be generated from the binary Ising model if the global minimum field energy criteria is used to terminate the sampler. Implications for texture synthesis are discussed.
The quality of a solder joint is determined based on its shape;a thin flat shaped joint is desirable and a fat round shaped joint is unacceptable. The photometric sampling method extracts roughness and shape of surfac...
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ISBN:
(纸本)081863880X
The quality of a solder joint is determined based on its shape;a thin flat shaped joint is desirable and a fat round shaped joint is unacceptable. The photometric sampling method extracts roughness and shape of surfaces from a sequence of images taken under a moving light source from a single fixed viewing direction. We have previously proposed a recovering algorithm for smooth surfaces. Surface reflection consists of three components;specular spike, specular diffuse, and Lambertian. Among these three components, the previous algorithm only can handle surfaces of the specular spike and the Lambertian. This paper proposes a novel algorithm to recover roughness and shape of specular diffuse lobe dominant surfaces.
We address in this paper the problem of establishing trajectories of objects in a long image sequence, in the case of occlusion, disocclusion of objects, and crossing trajectories and junctions. Two complementary crit...
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ISBN:
(纸本)0818638826
We address in this paper the problem of establishing trajectories of objects in a long image sequence, in the case of occlusion, disocclusion of objects, and crossing trajectories and junctions. Two complementary criteria have been investigated to come to the decision of linking two partial pieces of trajectory, that could come from a single object in motion: the continuity of the global trajectory, and the continuity of the velocity of the moving object. Experiments have been conducted on long sequences of real images. Complete trajectories are successfully recovered.
This paper describes the application of a new Spatial-Domain Convolution/ Deconvolution transform (S transform) for determining distance of objects using image defocus. The method known as STMAP involves simple local ...
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ISBN:
(纸本)081863880X
This paper describes the application of a new Spatial-Domain Convolution/ Deconvolution transform (S transform) for determining distance of objects using image defocus. The method known as STMAP involves simple local operations on only two images taken with different aperture diameters and can be easily implemented in parallel. Both images can be arbitrarily blurred and neither of them needs to be a focused image taken with a pin-hole camera. STMAP has been implemented on an actual camera system named SPARCS. EXperimental results on a real-world planar objects are presented. The results indicate that STMAP is useful in practical applications. The utility of the method is demonstrated for rapid autofocusing of electronic cameras. STMAP is computationally more efficient than other Depth-from-Focus methods and the results are comparable to a Fourier Transform based approach.
We propose a novel method to analyze a sequence of color images. A series of color images are examined in a four dimensional space, which we call the temporal-color space, whose axes are the three color axes (RGB) and...
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ISBN:
(纸本)081863880X
We propose a novel method to analyze a sequence of color images. A series of color images are examined in a four dimensional space, which we call the temporal-color space, whose axes are the three color axes (RGB) and one temporal axis. The significance of the temporal-color space lies in its ability to represent the change of image color with time. A conventional color space analysis yields the histogram of the colors in an image, only at an instance of time. Conceptually, the two reflection components from the dichromatic reflection model, the specular reflection component and the body reflection component, from two subspaces in the temporal-color space. These two components can be extracted by principal component analysis. Using this fact, we analyzed real color images and separated the two reflection components successfully. We did not make any assumptions about surface properties or the global distribution of surface normals. Finally object shape was recovered.
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