In this paper, a number of spatial/spatial-frequency image representations are reviewed. Wavelets have recently generated much interest, both in applied areas as well as in more theoretical ones. Wavelet transform rel...
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ISBN:
(纸本)0819413208
In this paper, a number of spatial/spatial-frequency image representations are reviewed. Wavelets have recently generated much interest, both in applied areas as well as in more theoretical ones. Wavelet transform relative to some basic wavelets provides a flexible time- frequency window which automatically narrows when observing high frequency phenomena and widens when studying low frequency environments. As a result, it is suitable for visual information representation. Applications in computervision such as image compression and image enhancement are examined. method is presented, in which, a N X N subimage is divided into a lot of N X 7 or N X 9 narrow image regions perpendicular to local fringe direction, and then each region is segmented by a corresponding threshold curve. Because the threshold curves can follow fringe's extremum changes, it can avoid the effect of the inhomogeneous grey level distribution caused by diffraction halo and accurate segmen space, a projection operator is used in the spatial-variant deconvolution. Nevertheless, experimental results show that this approximation mechanism can generate the depth map of different images successfully.
In this paper, we propose a method for quantitatively analyzing the performance of tracking algorithms for generic objects (objects about which the system has no prior knowledge). The sensitivity of algorithms are mea...
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ISBN:
(纸本)0819413216
In this paper, we propose a method for quantitatively analyzing the performance of tracking algorithms for generic objects (objects about which the system has no prior knowledge). The sensitivity of algorithms are measured as a function of changes in scale, rotation, clipping, and brightness. We then compare our quantitative measures with a subjective evaluation of the algorithm's performance on real-world images. We use a simple color-based matched filtering algorithm to illustrate the method.
Photochromic materials exist in two different color states, with switching between states being achieved by irradiation, with ultra-violet and visible light. By printing patterns and data using both photochromic ink a...
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ISBN:
(纸本)0819413208
Photochromic materials exist in two different color states, with switching between states being achieved by irradiation, with ultra-violet and visible light. By printing patterns and data using both photochromic ink and ordinary ink, it is possible to create a document that is difficult to forge and easy to authenticate. Security is achieved only by public ignorance about and the relative rarity of photochromic materials. Very high levels of security are possible, using modern data encipherment techniques. These are so secure that no known algorithmic method exists for breaking them in a practical amount of time. It should be understood that encipherment algorithms provide a way of protecting a message. Guaranteeing the authenticity of a complete document is better achieved using photochromic materials. This article describes a scheme which employs both techniques to achieve higher overall security than either can provide individually. Central to this idea is the ability to sense the presence of photochromic materials using machines, prior to recognizing specified patterns and reading text.
The paper is devoted to robot accuracy improvement via calibration and contains correspondent algorithms, hard- and software description. The experimental part of this work has been performed with PUMA robots. The har...
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ISBN:
(纸本)0819413216
The paper is devoted to robot accuracy improvement via calibration and contains correspondent algorithms, hard- and software description. The experimental part of this work has been performed with PUMA robots. The hardware includes a sensor unit mounted on the robot arm consisting of a CCD camera and four optical proximity sensors. The proposed algorithm is based on an integral estimate of straight path distortions and minimization of them by altering the parameters of the robot model.
One of the central problems of computervision is object recognition. A catalogue of model objects is described as a set of features such as edges and surfaces. The same features are extracted from the scene and match...
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ISBN:
(纸本)0819413208
One of the central problems of computervision is object recognition. A catalogue of model objects is described as a set of features such as edges and surfaces. The same features are extracted from the scene and matched against the models for object recognition. Edges and surfaces extracted from the scenes are often noisy and imperfect. In this paper algorithms are described for improving low level edge and surface features. Existing edge extraction algorithms are applied to the intensity image to obtain edge features. Initial edges are traced by following directions of the current contour. These are improved by using corresponding depth and intensity information for decision making at branch points. Surface fitting routines are applied to the range image to obtain planar surface patches. An algorithm of region growing is developed that starts with a coarse segmentation and uses quadric surface fitting to iteratively merge adjacent regions into quadric surfaces based on approximate orthogonal distance regression. Surface information obtained is returned to the edge extraction routine to detect and remove fake edges. This process repeats until no more merging or edge improvement can take place. Both synthetic (with Gaussian noise) and real images containing multiple object scenes have been tested using the merging criteria. Results appeared quite encouraging.
Color images can be analyzed using two kinds of coordinate systems: rectangular systems based on primary colors (RGB), and cylindrical systems based on hue, saturation, and intensity (HSI). HSI systems match our intui...
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ISBN:
(纸本)0819413208
Color images can be analyzed using two kinds of coordinate systems: rectangular systems based on primary colors (RGB), and cylindrical systems based on hue, saturation, and intensity (HSI). HSI systems match our intuitive understanding of colors and make it possible to name colors in knowledge bases, a significant advantage given the mushrooming use of declarative knowledge for image analysis. On the other hand, HSI systems give rise to singularities which result in undesirable instabilities, notably with respect to the statistical properties of hue distributions. Computing the mean and variance of a split distribution in the conventional manner would yield an unrealistically large variance and a mean hue in the blue-green region. The paper presents alternative ways of computing means and variances that avoid these effects. At the cost of a relatively slight numerical overhead, these computations generate results in agreement with our intuitive understanding of colors in split peak situations, and reduce to the standard definitions in well-behaved histograms. Recursive formulas are given for the calculation of these statistics, and an efficient algorithm is presented. Equivalence conditions between the results of the introduced procedures and conventional calculations are stated. Examples are given using actual color images.
The development of software that would be to computervision what expert system shells are to expert systems has been the subject of considerable inquiry over the last ten years; this paper reviews the pertinent publi...
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ISBN:
(纸本)0819413208
The development of software that would be to computervision what expert system shells are to expert systems has been the subject of considerable inquiry over the last ten years; this paper reviews the pertinent publications and tries to present a coherent view of the field. We start by outlining two major differences between would be `vision shells' and conventional expert system shells. The first is the need for an intermediate level of symbolic representation between image pixels and the knowledge base. The second is that the mental operations that people perform to interpret images lie almost totally below the threshold of consciousness. vision system designers therefore cannot, as domain experts normally do, examine their own mental processes and cast them into rules to extract information from images. The vision shell should thus contain, in addition to the usual knowledge engineering toolbox, knowledge on the pertinence of specific imaging operations towards various goals. After a review of the role of explicit knowledge in artificial vision, we examine the architecture a vision shell should have, and look at ways of facilitating the entry of domain-pertinent knowledge into it. Final remarks are made on knowledge representation and acquisition aspects particular to industrial applications.
A fundamental task in studying the action of cancer chemotherapy is to determine the quantity and spatial relationship of tumor-infiltrating lymphocyte populations. Classically this is performed by staining thin tissu...
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ISBN:
(纸本)0819413208
A fundamental task in studying the action of cancer chemotherapy is to determine the quantity and spatial relationship of tumor-infiltrating lymphocyte populations. Classically this is performed by staining thin tissue sections with antibodies by immunoperoxidase amplification. The staining technique is practically limited to locating a single cell type per tissue section. Full immunophenotyping requires successive staining of serial sections, using statistical analysis to correlate the results. This paper describes a system that brings together multi- parameter fluorescence imaging and morphological segmentation techniques to provide a fast, accurate, and automatic analysis of the lymphocyte infiltrate in tissue sections. With fluorescence techniques a single section can be stained with up to four distinct fluorescently labelled antibodies to determine cell phenotypes. To harness this potential computervisiontechniques are required to analyze the images. A routine based on the water shed algorithm has been developed that segments the nuclei image with an accuracy of greater than 90%. By matching the nuclei boundaries to the local peak fluorescence, cell boundary estimates are obtained in the antigen images. By then extracting two measurements from the boundary signal the cells can be classified according to their antigen expression. Determining cell expression of multiple antigens simultaneously provides a more detailed and accurate picture of the tumor infiltrate than single parameter analysis, and increases understanding of the immune response associated with the chemotherapy.
Due to delays in image acquisition and processing, prediction is a critical factor for successful visual tracking of moving objects (both for humans and for vision machines). This paper explores some alternative techn...
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ISBN:
(纸本)0819413216
Due to delays in image acquisition and processing, prediction is a critical factor for successful visual tracking of moving objects (both for humans and for vision machines). This paper explores some alternative techniques for predicting object motion for the purpose of tracking with an active camera system. In particular, one of our goals is to develop a system that will track an object undergoing `random' motion quite well, but that will track much better (at higher speeds with less lag) if the object settles into a periodic motion of some kind. Rather than identify parameters for specific signal models to accomplish this, we propose to use a finite set of previous joint states for the signal model. The advantages and problems associated with this approach are discussed. Results of experiments using different prediction algorithms with TRICLOPS, a high-performance active vision system, are also presented.
Advanced courses in the areas of Machine Perception and Machine Intelligence are not easy to prepare or conduct due to the dynamic research nature of the field. In engineering, our interest is in the construction of i...
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Advanced courses in the areas of Machine Perception and Machine Intelligence are not easy to prepare or conduct due to the dynamic research nature of the field. In engineering, our interest is in the construction of intelligent machines in the form of robotic devices or through computer simulation models. Studies in this area are further complicated by the broad range of disciplines that must be accessed in order to provide adequate coverage. This discussion focuses on a set of computer simulation projects that have been assigned at various times during offerings of an advanced graduate level course entitled Machine Perception. The format of the projects are presented with discussion of student results. The projects were novel in that they require advanced techniques of machine vision and are open-ended in that there are no specific solutions. The problems represent the mainstream of machine perception research without requiring more effort than is possible in a one semester course. Students responded with algorithms developed in a variety of computer languages and on various machines.
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