共查询到19条相似文献,搜索用时 109 毫秒
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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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联合击中击不中变换相关器 总被引:9,自引:3,他引:6
将联合击中击 中变换相关器用于二值图像的目标识别。与常用的联合变换相关器相比,联合击中击不中变换相关器对联合变换相关器输入图像和参考图像进行互补编码。编码的目的在于通过联合变换相关器来一步实现形态学中的击中击不中变换。 相似文献
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使用振幅调制和功率谱相减的联合变换相关器作多目标检测 总被引:4,自引:2,他引:2
提出一种使用振幅调制和功率谱相减的联合变换相关器作多目标检测,这一方法对联合功率谱作了修正,先将联合功率谱减去纯输入景物的功率谱和参考图象的功率谱,再将所得修正的联合功率谱乘以振幅调制滤波函数。分析和量化了输入景物噪声对联合变换相关器性能的影响。这种方法比条纹调节的联合变换相关器和修正的条纹调节的联合变换相关器能产生更好的相关输出和适应输入景物噪声的能力。 相似文献
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为了充分利用光学相关识别系统的空间-频谱带宽,提高光学相关识别技术的并行处理效率和识别准确度,提出了基于功率谱压缩-平移算法的多通道联合变换相关识别方法,该方法将峰值位置变化的标准差作为相关识别的判据.在输入空间光调制器的不同区域加载场景图像和N幅参考图像,然后在图像上分别叠加经迭代算法优化的相位模板,使得场景图像的傅里叶谱和每一幅参考图像的傅里叶谱在频谱面的不同空间区域相干叠加.调节相位优化算法的约束参量,使得每个通道的联合变换功率谱互不干扰,可实现N个通道的并行处理.分析了不同优化相位的傅里叶谱的局域峰值杂波均值和相关输出的峰值位置变化标准差之间的关系,并将其作为相位优选的依据.研究结果表明,在所提实验和数值模拟参数条件下,多通道联合变换相关识别系统可以在不增加经典相关识别系统复杂度的前提下,实现16通道的并行处理,这对光学相关器的实用化具有重要意义. 相似文献
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分析了联合广义分数傅里叶变换相关器相关峰的特性,得到通过改变广义分数傅里叶变换的系统参量可以提高广义分数相关峰性能的结论.进行了数值模拟和光学实验,并根据两者的结果对四个相关峰的性能指标相关峰强度最大值、峰能比、识别能力、信噪比进行了比较分析,说明只要适当控制系统参量,联合广义分数傅里叶变换相关器比联合分数傅里叶变换相关器具有更好的相关性能,有助于提高光学相关器识别的准确率. 相似文献
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复杂背景目标自动识别谱面处理技术研究 总被引:3,自引:0,他引:3
应用光电混合联合变换相关器对目标进行探测和识别时,由于实际拍摄的图像背景非常复杂,对比度较低,亮度不足等原因,使得相关峰很弱甚至根本得不到相关峰,不能达到探测和识别的目的.为此提出在光电混合联合变换相关器的功率谱面应用小波变换处理技术,有效地抑制了联合变换功率谱中的噪声干扰,提高了有用信息衍射光的能量,从而增强了应用光电混合联合变换相关器对复杂背景目标进行探测和识别的能力.实验证明利用经过小波变换处理后的联合变换功率谱所获得相关峰的对比度,较处理前由联合变换功率谱所获得相关峰的对比度能够达到百分之百的增强效果.作为实例文中给出了湖中小船处理前后的光学实验结果,从实验结果中可以明显看出此种处理方法的有效性. 相似文献
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The joint transform correlator (JTC) is one of the two main optical image processing architecture which provides a highly effective way of comparing images in a wide range of applications. Traditionally, an optical correlator is used to compare an unknown input scene with a pre-captured reference image library, to detect if the reference occurs within the input. Strength of the correlation signal decreases rapidly as the input object rotates or varies in scale relative to the reference object. The aim of this paper is to overcome the intolerance of the JTC to rotation and scale changes in the target image. Many JTC systems are constructed with the use of ferroelectric liquid crystal (FLC) spatial light modulators (SLMs) as they provide fast two-dimensional binary modulation of coherent light. Due to the binary nature of the FLC SLMs used in the JTC systems, any image addressed to the device need to have some form of thresholding. Carefully thresholding the grey scale input plane and the joint power spectrum (JPS) has significant effect on the quality of correlation peaks and zero order (DC) noise. A new thresholding technique to binarise the JPS has been developed and implemented optically. This algorithm selectively enhances the desirable fringes in the JPS which provide correlation peaks of higher intensity. Zero order noise is further reduced when compared to existing thresholding techniques.Keeping in mind the architecture of the JTC and limitations of FLC SLMs, a new technique to design rotation and scale invariant binary phase only filters for the JTC architecture is presented. Filers design with this technique have limited dynamic range, higher discriminability among target and non-target objects, and convenience for implementation on FLC SLMs. Simulation and experiments shows excellent results of various rotation and scale invariant filters designed with this technique. A rotation invariant filter is needed for various machine vision applications of the JTC. By fixing the distance between camera and input object, the scale sensitivity of the correlator can be avoided. In contrast to the industrial machine vision applications, scale factor is very important factor for the applications of the JTC systems in defence and security. A security system using a scale invariant JTC will be able to detect a target object well in advance and will provide more time to take a decision. 相似文献
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对联合变换相关器的功率谱进行对数变换可强化其高频分量,锐化相关峰,但同时也会增强其噪声成分,影响抗噪性能。针对这一问题,提出了一种改进的对数联合变换相关器模型。通过改变对数函数形式来提高对数联合变换相关器的抗噪能力。计算机仿真结果表明,在附加高斯白噪声、非重叠低频和高频有色噪声的条件下,改进的对数联合变换相关器的抗噪能力均优于传统的对数联合变换相关器。 相似文献
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A new optical security system is proposed using a shifted phase-encoded joint transform correlation (JTC) architecture. In the proposed technique, at first, the address code is fed into two channels where one channel is shifted by 180°. The output signals from both the channels are phase-masked and then added with the input image to be encrypted. The joint power spectrum (JPS) obtained from one channel is subtracted from the JPS of the other channel, and the modified JPS is inverse Fourier transformed to yield the encrypted image. For decryption, the received signal is Fourier transformed and multiplied by the phase mask and the address code, which is then inverse Fourier transformed to generate the output signal. The proposed technique does not require complex conjugate of the address code otherwise required in the classical double random phase encryption. Also the decryption result is much more enhanced when compared to the output generated by alternate JTC techniques. Computer simulation results verify that the encryption and decryption are very much secure and efficient in both noise-free and noisy conditions. 相似文献
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Performances of an all-optical subtracted joint transform correlator that uses a photorefractive crystal 总被引:1,自引:0,他引:1
An all-optical subtracted joint transform correlator (JTC) was proposed and it was experimentally shown that the correlator successfully performs the pattern recognition with the number of reference patterns. In the correlator, an optical interferometer was introduced to remove the additional correlation signals between the reference patterns themselves from the output plane and a photorefractive crystal was also introduced to record the joint power spectra as volume holograms. The processing for removing the additional correlation signals was performed by the parallel computations in the interferometer in real time. In this study it has been found that the correlator yields significantly better correlation results than the classical joint transform correlator does and the recording of the volume hologram corresponds to a nonlinear processing of the joint power spectrum in the fringe-adjusted joint transform correlator. However the volume hologram has angular selectivity for matching the Bragg condition. It would restrict the shift-invariant area of the input image plane. This restriction has been investigated experimentally. 相似文献
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Leonid I. Muravsky Olexander P. Maksymenko Olexander M. Sakharuk 《Optics Communications》2004,240(4-6):275-291
The optical speckle–displacement correlation technique (OSDCT) is proposed for study of in-plane speckle displacements. The joint transform correlator architecture is used to evaluate the displacements of speckle subimages of strained surfaces. The procedure of the correlation response producing as a result of cross-correlation of strainless and strained surfaces in a conventional joint transform correlator (JTC) is considered. The convenient techniques for a joint power spectrum transformation are selected. The systematic and random errors of a mean speckle pattern displacement of a rigid body motion calculated by using the OSDCT and the digital speckle–displacement measurement technique are compared. The robustness of some JTC versions (a conventional JTC, a JTC with median thresholding, a JTC with subset median thresholding, and a fringe adjusted filter JTC) to input noise of speckle patterns and output noise of a correlation response is studied. 相似文献
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Joewono Widjaja 《Optics Communications》2012,285(6):1029-1034
A new method for noisy face recognition by incorporating wavelet filter into compression-based joint transform correlator (JTC) is proposed. The simulation results show that the proposed method has advantages over the conventional compression-based JTC in that regardless of the contrast and the noise level of the target, the wavelet filter can optimize the recognition performance to be higher than the classical JTC, provided compressed references have high contrast. 相似文献
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为增强联合变换相关器输入面图像去噪和边缘检测的可调节性,改善相关器的识别效果,将形态学算法引入输入面图像去噪和边缘检测,提出利用形态学边缘检测的宽度可调节性来改善联合变换相关器的识别效果。计算机模拟表明,改进后的算法是有效的。 相似文献
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Multiple target detection using a fringe-adjusted and power spectrum subtracted joint transform correlator is proposed. The best factor of the filter to deliver the best correlation output performance is found through computer simulation tests and the result is verified by a programmable single spatial light modulator joint transform correlator. The technique is found to deliver a better correlation output and the capacity to accommodate noise in the input scene than the classical, the previous fringe adjusted and modified fringe adjusted joint transform correlators. 相似文献
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GAO Zehua HUANG Xianlie CHEN Chao 《Chinese Journal of Lasers》1999,8(3):249-256
1IntroductionForopticalpaternrecognition,thejointtransformcorelator[1](JTC)ismoresuitableforrealtimeopticalpaternrecognitiona... 相似文献