共查询到16条相似文献,搜索用时 109 毫秒
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《光学学报》2017,(11)
提出基于小波变换的优化折中综合鉴别函数(OTSDF)滤波器(W_OTSDF)算法,对其进行优化设计,利用小波变换的多尺度与带通滤波特性,提高平面集成2f光学相关器的相关输出峰值强度和信噪比(SNR)。利用Matlab搭建系统的仿真模型,获取W_OTSDF滤波器的优化算法。仿真结果表明,在平面集成2f系统中对旋转、缩放以及旋转缩放同时存在的畸变目标进行识别时,优化设计的W_OTSDF滤波器较OTSDF滤波器在峰值相关能量比(PCE)、峰值旁瓣比(PSR)、SNR等整体性能指标方面均有较大提高。理论分析与仿真结果均表明W_OTSDF滤波器较OTSDF滤波器具有更好的识别效果。 相似文献
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为解决目标识别技术中混合畸变目标的识别难题,提出了一种面积极坐标变换算法.该算法利用相似图形尺寸与面积的满射函数关系和极坐标变换的旋转不变特性,对目标与模板同时进行面积变换和极坐标变换.将面积极坐标变换算法与基于形态学膨胀的边缘加粗处理算法相结合应用于光电混合联合变换相关器,实现了大尺度混合畸变目标的识别.以空中飞机为例,光学相关实验表明,该方法可显著提高混合畸变目标的相关峰强度,旋转畸变容差为0°~100°,比例畸变容差为100%~200%,具有较大尺度的混合畸变容差,扩大了识别范围.其混合畸变识别能力优于极坐标对数变换算法与综合鉴别函数法其衍生方法,其"时间复杂度"远小于综合鉴别函数及其衍生方法. 相似文献
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光学相关器在自动目标识别中的应用 总被引:2,自引:2,他引:0
为使光学相关器更好地应用于自动目标识别领域,保证在较高识别速度下,具备良好的识别效果,介绍了应用于自动目标识别领域的联合变换相关器和匹配滤波相关器.针对匹配滤波相关器实现过程中的两项关键技术,在滤波器编码技术上提出了构造等相关峰综合鉴别函数以解决畸变不变识别问题.在相关峰识别技术上,针对阈值法存在的不足,提出利用BP神经网络对相关平面相关峰进行识别,采用划分感兴趣区域的方法减少了输入层神经元数目,简化了神经网络结构.借助搭建的光学相关器系统验证了该方法可对相关信号和噪声进行有效分类,提高了光学相关器的识别效果. 相似文献
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非重叠背景噪声下的自适应维纳滤波模式识别方法 总被引:4,自引:0,他引:4
维纳滤波实现模式识别的关键问题是噪声知识的获得与估计。提出一种非重叠背景噪声的提取方法,首先将对噪声的粗略估计代入维纳滤波函数,得到相关峰。然后由相关峰的位置及参考图像的尺寸确定目标图像的位置和范围,从而提取出背景噪声图像。经过二次维纳滤波,得到改善的相关输出结果,实现了自适应过程。仿真结果表明在非重叠有色噪声环境下,与噪声估计法以及传统的维纳滤波方法相比,此方案具有较好的识别效果。 相似文献
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We consider a new approach for enhancing the discrimination performance of the VanderLugt correlator. Instead of trying to optimize the correlation filter, or propose a new decision correlation peak detection criterion, we propose herein to denoise the correlation plane before applying the peak-to-correlation energy (PCE) criterion. For that purpose, we use a linear functional model to express a given correlation plane as a linear combination of the correlation peak, noise, and residual components. The correlation peak is modeled using an orthonormalized function and the singular value decomposition method. A set of training correlation planes is then selected to create the correlation noise components. Finally, an optimized correlation plane is reconstructed while discarding the noise components. Independently of the filter correlation used, this technique denoises the correlation plane by lowering the correlation noise magnitude in case of true correlation and decreases the false alarm rate when the target image does not belong to the desired class. Test results are presented, using a composite filter and a face recognition application, to verify the effectiveness of the proposed technique. 相似文献
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We have investigated decoherence in Josephson-junction flux qubits. Based on the measurements of decoherence at various bias conditions, we discriminate contributions of different noise sources. We present a Gaussian decay function extracted from the echo signal as evidence of dephasing due to 1/f flux noise whose spectral density is evaluated to be about (10(-6)Phi0)2/Hz at 1 Hz. We also demonstrate that, at an optimal bias condition where the noise sources are well decoupled, the coherence observed in the echo measurement is limited mainly by energy relaxation of the qubit. 相似文献
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The effect of the correlation function of noise sources derived from the ocean wave spectrum on the vertical spatial correlation of ocean ambient noise is investigated. The spatial correlation models of ocean ambient noise usually assume that the surface noise sources are uncorrelated. This assumption can be used to explain some physical phenomena, but it is not consistent with the real situation. Considering the relation between the ocean wave motion and the ambient noise generated by wind, the spectrum of ocean wave is introduced to calculate the vertical correlation of ocean ambient noise as the correlation function of noise sources by using the Kuperman-Ingenito(K/I) noise model. The comparison of the simulations and the experimental data shows that the simulations of vertical correlation of ambient noise have some differences with the experimental data by assuming the noise sources are uncorrelated and the simulations of vertical correlation of ambient noise have a good agreement with the experimental data by using the correlation function of noise sources derived from the ocean wave spectrum under the situation of high wind speed. 相似文献
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研究了由海浪谱导得的噪声源的相关函数对海洋环境噪声垂直空间相关性的影响。常用的海洋环境噪声空间相关性模型一般假设海面噪声源是非相关的,这种假设可以解释一些物理现象,但是与真实情况并不符合。考虑到风成噪声与海浪运动的相关性,引入海浪谱,得到噪声源的相关函数,利用Kuperman-Ingenito (K/I)噪声模型,计算海洋环境噪声的垂直相关性。通过仿真结果与实验数据对比可以看出,在高风速下,假设噪声源不相关时计算得到的噪声场垂直相关性与实验结果相差较大,而利用由海浪谱导得的噪声源的相关函数计算得到的噪声场的垂直相关性与实验结果符合较好。 相似文献
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Mohammed Nazrul Islam K. Vijayan Asari Mohammad S. Alam 《Optics Communications》2011,284(6):1532-1539
This paper proposes a novel pattern recognition system for invariance to noise and distortions. The technique first generates a synthetic discriminant function of the target image from its different distorted versions. It then takes four different phase-shifted versions of the reference image, which are individually joint transform correlated with the given input scene. Thus the proposed algorithm produces a single cross-correlation signal corresponding to each potential target. Also a fringe-adjusted filter is designed to generate a delta-like correlation peak with high discrimination between the signal and the noise. The pattern recognition system is also designed for the identification of multiple targets belonging to multiple reference objects simultaneously in a given input scene. The proposed technique is investigated using computer simulation including real-life images in different complex environments. 相似文献