The authors proposed the localization of some kinds of generalized cylinders from their brightness image by solving the inverse perspective transform of their contours. Geometrical properties of perspective projection...
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ISBN:
(纸本)081861952x
The authors proposed the localization of some kinds of generalized cylinders from their brightness image by solving the inverse perspective transform of their contours. Geometrical properties of perspective projection of zero-curvature points of space or planar curves are used for that. The main geometrical properties are exploited in two experiments. These experiments involve straight homogeneous cylinder and objects of revolution with a scaling function having at least one zero-curvature point. Knowing the model of these objects, it is shown that their spatial attitude can be recovered from their perspective image.
The author describes a technique for automated inspection of solder bumps by analyzing spatial features and intensity characteristics of image highlights. It is based on high-contrast imaging of specular soldered surf...
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ISBN:
(纸本)081861952x
The author describes a technique for automated inspection of solder bumps by analyzing spatial features and intensity characteristics of image highlights. It is based on high-contrast imaging of specular soldered surfaces against a reflective background using dark-field illumination for selective enhancement of surface topography. Bright-field images of these surfaces are also analyzed to resolve ambiguities in the defect-identification process. The reflectance of solder is studied under various illumination and imaging constraints, for the estimation of corresponding signatures of image specularities, which provide information about surface curvature, metallurgical constituents (such as contaminants in the solder alloy), and topographic discontinuities (such as ridges and cavities). During inspection, a specular highlight in the run-time image is mapped into a feature space of reduced dimensionalities for comparison against the features of typical signatures. Based on this principle, vision systems have been designed and implemented for high-speed detection of defective solder bumps on leadless ceramic chip carriers and metallized advanced VLSI wafers, with significant improvement in process reliability.
Stereo matching is the process of determining correspondences between entities in related images. Often, this is treated as two quite independent subprocesses, namely, segmentation, followed by matching. These process...
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ISBN:
(纸本)081861952x
Stereo matching is the process of determining correspondences between entities in related images. Often, this is treated as two quite independent subprocesses, namely, segmentation, followed by matching. These processes are treated as naturally related, in that partial matching is fed back to the segmentation and both proceed simultaneously in a cooperative fashion. Regions are considered as the primitives to be matched, since many of the shortcomings inherent in approaches based on points or lines can be overcome by taking more developed entities. The implementation is based on maintaining a hierarchy of segmented regions in each image, corresponding to analysis at differing scales. The selection of a particular segmentation in each image at a scale appropriate to each region is validated with reference to the optimal matching region in the other image. Examples of these methods, applied to a synthetic image (incorporating color) and to natural office scenes, are presented.
A set of array processors with optical interconnection networks for fine-grain imageprocessing is considered. The unit-time interconnection made possible with the use of free-space optics results in efficient solutio...
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ISBN:
(纸本)081861952x
A set of array processors with optical interconnection networks for fine-grain imageprocessing is considered. The unit-time interconnection made possible with the use of free-space optics results in efficient solutions to communication-intensive imagecomputations. Using these models, a summary of results in designing O(log N) pointer-based algorithms for several tasks in low- and medium-level vision are presented, along with a generic subroutine that can be used to simulate algorithms for imagecomputations on the proposed electrooptical arrays.
A computational approach to locating human faces in newspaper photographs is described. While the computational recognition of a well-framed face as belonging to one of a known set of faces has received some attention...
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ISBN:
(纸本)081861952x
A computational approach to locating human faces in newspaper photographs is described. While the computational recognition of a well-framed face as belonging to one of a known set of faces has received some attention, the computational location of faces in varying contexts is relatively unexplored. Candidates for the locations of faces are hypothesized by extracting features in the edge-image of the photograph and matching with a model of a face profile. A face is defined by a parametric representation of each of the component parts. Knowledge contained in the caption is represented using semantic networks and is used to reason about the locations of faces of individuals in the photograph.
The authors present a method to smooth a signal - whether it is an intensity image, a range image, or a contour - which preserves discontinuities and thus facilitates their detection. This is achieved by repeatedly co...
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ISBN:
(纸本)081861952x
The authors present a method to smooth a signal - whether it is an intensity image, a range image, or a contour - which preserves discontinuities and thus facilitates their detection. This is achieved by repeatedly convolving the signal with a very small averaging filter modulated by a measure of the signal discontinuity at each point. This process is related to the anisotropic diffusion reported by P. Perona and J. Malik (1987) but it has a much simpler formulation and is not subject to instability or divergence. Real examples show how this approach can be applied to the smoothing of various types of signals. The detected features do not move, and thus no tracking is needed. The last property makes it possible to derive a novel scale-space representation of a signal using a small number of scales. Finally, this process is easily implemented on parallel architectures: the running time on a 16K connection machine is three orders of magnitude faster than on a serial machine.
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.
Pentland (1987) proposed an algorithm for sensing scene depth by measuring the amount of defocus of an image. The algorithm is interesting in the sense that no correspondence problems are involved. The authors discuss...
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ISBN:
(纸本)081861952x
Pentland (1987) proposed an algorithm for sensing scene depth by measuring the amount of defocus of an image. The algorithm is interesting in the sense that no correspondence problems are involved. The authors discuss the difference between shape from defocus and shape from focus and then present a two-phase algorithm where the defocus process is modeled as a two-dimensional Gaussian point-spread function. During the first phase (calibration phase), a camera system parameter is determined off-line. In the next phase (depth-recovery phase), this parameter is used to recover on-line the scene depth by taking two images of the same scene, but with a different amount of defocus. Some implementation issues are addressed, and test results on real images are provided.
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 neural-network (NN) approach for translation-, scale-, and rotation-invariant recognition of objects is presented. The network utilized is a multilayer perceptron (MLP) classifier with one hidden layer. Backpropagat...
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ISBN:
(纸本)081861952x
A neural-network (NN) approach for translation-, scale-, and rotation-invariant recognition of objects is presented. The network utilized is a multilayer perceptron (MLP) classifier with one hidden layer. Backpropagation learning is used for its training. The image is represented by rotation-invariant features which are the magnitudes of the Zernike moments of the image. To achieve translation and scale invariancy, the image is first normalized with respect to these two parameters using its geometrical moments. The performance of the NN classifier on a database consisting of binary images of all English characters is reported and compared to those of nearest-neighbor and minimum-mean-distance classifiers. The results show that (1) the MLP outperforms the other two classifiers, especially when noise is present;(2) the nearest-neighbor classifier performs about the same as the NN for the noiseless case;and (3) the Zernike-moment-based features possess strong class separability power.
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