共查询到20条相似文献,搜索用时 343 毫秒
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矩作为描述图象的一种方式已在图象处理和模式识别过程中得到应用。本文基于 Hu 所定义的函数矩的方式提出了倒矩概念。文中列出了倒矩具有的一些性质。文中推出倒矩和中心矩之间的关系。从倒矩和中心矩之间的关系以及倒矩的性质中可以看到函数的一个特性在低阶倒矩得到反映后,相应它就不影响高阶倒矩,即一个特性仅在一个倒矩中得到反映。Hu 矩却没有这个特性。一个特性在低阶矩中出现后。它仍然在高阶矩中起作用。规一化过程只能消除部份特性的影响。因此可说,例矩是描述图象的一个较好参量,文中同时对物体旋转后的倒矩以及倒矩应用作了一些讨论。 相似文献
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用离散傅立叶-切比雪夫正交矩描述图像 总被引:1,自引:0,他引:1
提出了一种基于离散Fourier正交函数系与离散Chebyshev正交多项式的图像正交矩。分析了连续正交矩与离散正交矩的原理与重构方法,提出Fourier-Chebyshev正交矩的构造原理与图像重构方法。对Legendre矩与Zernike矩两种经典的图像矩与离散Fourier-Chebyshev正交矩做了对比实验。实验结果表明,在复杂图像的处理中,该矩具有比传统连续函数矩更好的特征表达能力。 相似文献
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K分布的参数估计研究对于雷达杂波特性预测和估计具有重要意义。基于矩估计的K分布参数估计方法通过联立不同阶原点矩进行参数求解,这些不同阶数下的联合,在数据长度受限情况下会产生误差。因此,通过计算原点矩偏导和原点矩之间的关系,推导出了一种新的K分布杂波参数估计方法。该方法在同阶原点矩的条件下进行参数估计,避免了不同阶原点矩之间的估计误差,具有更好的估计性能。通过仿真和实测杂波数据,分析比较了该方法与其他矩估计法的参数估计有效率和估计精度,该方法具有100%的估计有效率且估计精度更高。高阶矩对数据敏感,在矩估计法中应尽量选取低阶矩,通过合理选取阶数k可以得到较为理想的估计结果和精度。 相似文献
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基于伪zernike矩的不变性,提出了基于伪zernike矩特征提取的车牌字符识别方法。在车牌区域定位的基础上,通过对图像的二值化过程和字符图像分割等一系列处理,在进行归一化处理后分别提取伪zernike的高阶矩。将提取的伪zernike矩作为字符的特征描述输入到BP神经网络进行训练,最后进行车牌字符分类识别。通过实验证明了该方法的的可行性。测试结果表明,这种方法实用有效,识别效果优于HU矩和zernike矩。而且可以计算出错误率和可识别的最佳矩,减小了计算量且增强了字符识别的实时性。 相似文献
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基于组合矩的激光雷达距离像目标识别 总被引:2,自引:0,他引:2
激光成像雷达距离像与目标表面物理结构特性密切相关,体现目标的本质特征,是目标识别的主要研究方向。采用组合矩的神经网络方法进行了相干激光雷达距离像目标识别仿真研究。用Hu不变矩和仿射不变矩两者的低阶矩组合表示距离像目标区域特征,利用反向传播(BP)神经网络识别不同方位角的车辆。当视场角不变时,训练10个目标,每个目标取3~19个样本,在不同载噪比(CNR)情况下,分析Hu不变矩、仿射不变矩和两者组合矩的识别率。理论分析和仿真实验表明利用组合不变矩进行距离像目标识别性能优于单独利用其中一种不变矩。 相似文献
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Capacity and Character Expansions: Moment-Generating Function and Other Exact Results for MIMO Correlated Channels 总被引:1,自引:0,他引:1
Simon S. H. Moustakas A. L. Marinelli L. 《IEEE transactions on information theory / Professional Technical Group on Information Theory》2006,52(12):5336-5351
A promising new method from the field of representations of Lie groups is applied to calculate integrals over unitary groups, which are important for multiantenna communications. To demonstrate the power and simplicity of this technique, a number of recent results are rederived, using only a few simple steps. In particular, we derive the joint probability distribution of eigenvalues of the matrix GGdagger , with G a nonzero mean or a semicorrelated Gaussian random matrix. These joint probability distribution functions can then be used to calculate the moment generating function of the mutual information for Gaussian multiple-input multiple-output (MIMO) channels with these probability distribution of their channel matrices G. We then turn to the previously unsolved problem of calculating the moment generating function of the mutual information of MIMO channels, which are correlated at both the receiver and the transmitter. From this moment generating function we obtain the ergodic average of the mutual information and study the outage probability. These methods can be applied to a number of other problems. As a particular example, we examine unitary encoded space-time transmission of MIMO systems and we derive the received signal distribution when the channel matrix is correlated at the transmitter end 相似文献
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《IEEE transactions on information theory / Professional Technical Group on Information Theory》1975,21(3):301-309
It has long been known that for a mean-square error distortion measure the Gaussian distribution requires the largest rate of all sources of a given variance. It has also been stated that a code designed for the Gaussian source and yielding distortiond when used with a Gaussian source will yield distortionleq d when used with any independent-letter source of the same variance. In this paper, we extend these results in two directions: a) instead of assuming that the source has a fixed variance, we fix an arbitrary moment; b) instead of mean-square error distortion measures, we consider nearly arbitrary continuous difference distortion measures. For each moment constraint, we show that there is a given distribution that has the largest rate for (nearly) any difference distortion measure and that a code designed for this source yielding distortiond yields distortionleq d for any ergodic source satisfying the same moment constraint. Furthermore, digital encoding of the output of this encoder may yield a lower rate when this encoder is used with a source for which it was not designed. We also extend these results to the case of a random process or random field of known correlation function under a difference distortion measure. 相似文献
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In this paper we present the derivation of the bivariate distribution function for median filtered sequences of independent, arbitrary, second-order random variables. This result is then used to qualitatively analyze second moment properties of median filtered data. The results hint towards a low-pass characteristic of the median filters and a low dependency of the output spectrum on input alphabet size and distribution. 相似文献
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Rathi V. 《IEEE transactions on information theory / Professional Technical Group on Information Theory》2006,52(9):4212-4218
In this correspondence, we estimate the variance of weight and stopping set distribution of regular low-density parity-check (LDPC) ensembles. Using this estimate and the second moment method we obtain bounds on the probability that a randomly chosen code from regular LDPC ensemble has its weight distribution and stopping set distribution close to respective ensemble averages. We are able to show that a large fraction of total number of codes have their weight and stopping set distribution close to the average 相似文献
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通过逆矩法的估计方法,得到了定数截尾下双参数指数分布E(μ,A)中位置参数μ的逆估计量。模拟结果表明逆矩法估计量是可行的。同时,也得到构造位置参数区间估计的方法。 相似文献
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无线信号服从瑞利分布的验证方法 总被引:2,自引:2,他引:0
在信号传输系统中,对于空中传来的信号的包络是服从瑞利分布或者是莱斯分布的,然而对于怎么去判别却少有人提及。文章从统计理论的角度,根据:①参数估计中当总体的k阶矩存在时,样本的k阶矩依概率收敛于总体的k阶矩的性质;②概率密度函数拐点的特点;结合模糊估计的应用,运用了两种方法验证了空中传播信号服从瑞利分布。 相似文献
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A simple method of quantifying the ELF (extremely low frequency) magnetic field distribution around electric appliances, which takes the harmonics into account, is newly proposed. The proposed method involves: (1) a simple estimation of the position of an equivalent magnetic dipole moment inside an appliance, using two magnetic field meters; (2) identification of the amplitude of the dipole moment magnetic-field measurements at certain points; and (3) calculation of the magnetic field distribution around the appliance using the estimated dipole moment. In this method, the dipole moment vector is assumed to be a similar value by allowing an uncertainty of 6 dB in the estimated magnetic field, which enables easy estimation of the dipole moment. In addition, the frequency characteristics of the magnetic field are taken into account by considering the harmonic components in the magnetic field waveform. The proposed method was applied to 13 types of appliances, and their equivalent magnetic dipole moments and harmonic components were determined. The results revealed that the proposed method is applicable to many electric appliances. The conditions required for the adoption of the method were also clarified 相似文献
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《Geoscience and Remote Sensing, IEEE Transactions on》2008,46(9):2568-2583
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Roth R.M. Seroussi G. 《IEEE transactions on information theory / Professional Technical Group on Information Theory》2007,53(8):2760-2768
New lower bounds are presented on the second moment of the distance distribution of binary codes, in terms of the first moment of the distribution. These bounds are used to obtain upper bounds on the size of codes whose maximum distance is close to their minimum distance. It is then demonstrated how such bounds can be applied to bound from below the smallest attainable ratio between the maximum distance and the minimum distance of codes. Finally, counterparts of the bounds are derived for the special case of constant-weight codes. 相似文献
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提出了一种基于瞬时步态能量图的远距离身份识别算法.首先根据摆动距离计算出步态周期,并指定步态周期中的关键时刻.步态序列中一个关键时刻的所有侧面轮廓图的平均值构成一个平均瞬时图.一个关键时刻的瞬时步态能量图的计算利用了当前关键时刻以及其他关键时刻的平均瞬时图.提高了每个关键时刻侧面轮廓图像的质量,并比单纯使用步态能量图的方式增加了步态的运动信息.随后计算出所有关键时刻侧面轮廓图相对于瞬时步态能量图的偏移的累积图像,与步态能量图共同作为描述一个对象的特征向量.最后,使用最近邻算法进行步态特征分类.在USF步态数据库上对该算法进行实验,并与基线算法以及另外两个新的步态识别算法进行比较,结果显示该算法达到了更高的总体识别率. 相似文献