共查询到20条相似文献,搜索用时 62 毫秒
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变形雅可比(p=4,q=3)—傅立叶矩的抗噪声能力研究 总被引:3,自引:0,他引:3
使用加法性零均白噪声,从统计性重建误差、统计性信噪比和带噪声图像描述等方面分析了变形雅可比(p=4,g=3)—傅立叶矩(PJFM′S)的抗噪声能力。理论和实验都表明,该矩除了具有平移、灰度、尺度和旋转等多畸变不变性,还具有很强的抗噪声能力,性能优于其它图像矩,更适合用于多畸变不变图像的描述和识别。 相似文献
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一种广义正交不变图像矩:雅可比-傅立叶矩 总被引:1,自引:1,他引:0
提出一种多畸变不变的正交图像矩:雅可比-傅立叶矩.其核函数由径向雅可比多项式和角向傅立叶复指数因子组成.雅可比多项式中的两个参数p和q的变化能够形成各种正交多项式,因而形成各种正交图像矩:勒让德-傅立叶矩(p=1,q=1)、切比雪夫-傅立叶矩(p=2,q=3/2)、正交傅立叶-梅林矩(p=2,q=2)和Zernike矩以及变形Zemike矩,等等.因此雅可比-傅立叶矩是核函数由径向多项式和角向傅立叶复指数因子组成的正交图像矩的一般形式,为这种正交图像矩的数学分析和优化提供了理论基础. 相似文献
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印刷电路板光电图像畸变校正研究 总被引:1,自引:0,他引:1
为了校正因CCD摄像系统视场较大等原因产生畸变现象的印刷电路板(PCB)光电图像,提出了一种自适应控制的图像畸变校正方法。详细分析了存在几何畸变图像进行校正的基本原理,首先给出了畸变图像任一点坐标与校正图像对应点坐标之间的关系,然后以畸变图像与校正图像间控制点对的映射关系为基础,采用最小二乘法(LSM)、多项式拟合和双线性插值的灰度重建,由自适应控制关系找到畸变图像与校正图像控制点对的对应坐标,使发生几何畸变的图像得到有效校正。对方格测试图像和由CCD摄像系统获取的存在几何畸变的PCB光电图像进行了实际校正试验,结果证明了基本原理分析的正确性。 相似文献
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高精度图像尺寸检测镜头畸变校正方法与实现 总被引:1,自引:0,他引:1
在高精度轴类零件尺寸图像检测中,提出了一种基于标准件法对镜头径向畸变进行快速校正的方法。该方法通过建立世界坐标转换到摄像机坐标、然后再转换到图像坐标的理想数学模型,并引入径向畸变参数,最终确立物体在世界坐标中与图像坐标中的映射关系,从而建立误差补偿曲线的高次拟合函数。利用得到的误差补偿函数的系数矩阵和径向畸变参数,实现镜头畸变的误差校正,有效改善了镜头畸变造成的检测误差。实验表明,该方法快速有效,提高了检测精度、降低了设备成本、检测精度可达2 μm。 相似文献
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基于Zernike矩的三维目标多视点特性视图建模 总被引:9,自引:2,他引:7
目标的模型化是三维目标识别的一个重要环节。由于从多视点特征法建立的模型能够避免从二维图像中恢复目标的三维结构.在三维目标识别中应用比较广泛。使用镶嵌式多面体分割视觉空间以得到三维目标的多视点投影图像,采用较小的镶嵌单元尺寸以完备地描述目标各种姿态的信息。Zernike矩具有旋转不变性,并能够方便地由各阶矩重建图像。计算多面体各个单元的投影图像的Zernike矩.所需的矩的最高阶次由重建图像与原图像的差别确定,通过聚类方式合并那些图像的矩变化很小的投影对应的几个小单元.每个新单元可以提取一幅特性视图.实现较小数目的多视点特性视图的建模。实验证明了这种方法的可行性。 相似文献
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Perfect binary arrays have been the object of investigation by several authors in recent years. This Letter collects known results, including those obtained by combinatorialists in pursuit of a different objective, and applies them to given an account of the status of such arrays of size s*t with 1> 相似文献
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A novel, low-profile internal planar inverted-F antenna (PIFA) with broadband characteristics is proposed for GSM/DCS/UMTS/WiBro applications. Broadband characteristics are achieved by inserting an inverted-L patch, and a bent feed line ensures good impedance matching. The optimum design parameters of the proposed antenna are decided by parametric analysis. Good omnidirectional patterns with reasonable gains are achieved at each frequency band of interest 相似文献
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The m=0, n=0 mode of a rectangular waveguide is examined. It is demonstrated, through an example, that this mode, contrary to general acceptance, should be included in the analyses of waveguide slot discontinuities. 相似文献
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Interactivity = Reflective Expressiveness 总被引:1,自引:0,他引:1
All types of media influence our opinions, feelings, and mood. We consume it because it reinforces our behavior and we identify with roles and values in it. It educates, informs, and entertains us through both escapism and emotional release. In short, it shapes our lives. The technology that today lets us interact with nearly everyone about any topic fosters the broadcasting approach and drives our interactive behavior to a point of arbitrariness, where every media is appropriate for every kind of knowledge transfer. If that is so, can we get back to a place where users can make educated decisions about the appropriate use of media for communication? Or are the current tools sufficient? Are we happy to communicate with others through technology because it lets us hide behind it? We've assembled some ideas on the relationship between interactivity and media technology and drawn a few conclusions 相似文献
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The design of several two-port antenna systems for mobile phones is presented. All these structures are made up of two planar inverted-F antennas closely positioned on a small ground plane and radiating in the GSM900/DCS1800 and UMTS frequency bands. First, the antennas are simply associated at the top edge of the same printed circuit board. Thus, to improve their isolation and their total efficiency, a neutralisation effect is created by means of an optimised suspended line, which links the feeding strips of the radiators. The performance of these systems is measured and compared with theoretical results 相似文献
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The emergence of vastly refined algorithms for finite-element analysis, which are putting electromagnetic simulators into the hands of any engineer who can afford a personal computer, is discussed. Field simulation allows an engineer to analyze the electromagnetic behavior of a device without building a physical prototype and taking measurements. The way in which simulation technology is changing the design process is illustrated by considering the design of a coax-to-waveguide transition. The field simulation model developed by the design engineer is passed to the manufacturing engineer, who runs parameter studies of the device by varying key dimensions and materials to determine the sensitivity of device performance to these parameters. Further, the field simulation model helps determine the impact of unforeseen changes during manufacturing due to variations in supplies and facilities. The process used by the finite-element simulators to solve Maxwell's equations is described. Two typical CAE applications are examined: a microwave low-pass filter design and a study of electromagnetic coupling in digital circuit interconnections. Pointers for selecting electromagnetic CAE software are given 相似文献
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《Spectrum, IEEE》1992,29(8):29-35
Concerns about the main encrypting and enciphering schemes being proposed as a way to ensure data security are examined. To elucidate the issues involved, public-key cryptography is explained. The collision between the interests of government intelligence agencies and private groups as evidenced by the controversy over the Digital Signature Standard (DSS) proposed by the US National Institute of Standards and Technology is discussed. Weaknesses of the DSS and possible curbs on cryptography are addressed 相似文献