共查询到19条相似文献,搜索用时 312 毫秒
1.
基于联合子波变换的目标轮廓抽取技术 总被引:1,自引:1,他引:0
子波变换是目标特征抽取的有效方法。本文把联合变换相关技术与子波变换结合起来,建立了一套新的子波变换光学实验系统。推导了联合子波变换的基本理论,并给出了联合子波换相关器在目标特征抽取应用中的实验结果。 相似文献
2.
四通道实时联合变换相关器 总被引:2,自引:0,他引:2
提出把光学波阵面分割复用器用于单通道实时光电混合联合变换相关系统实现四通道实时相关,使单通道系统扩展为具有多个独立通道的系统,使系统的容量和处理速度提高数倍,使系统的性能得以改善。给出了新系统的设计方案、工作原理和实验结果。 相似文献
3.
空变菲涅耳联合变换相关器 总被引:3,自引:0,他引:3
提出了菲涅耳联合变换相关器(Fresnel Joint Transform Correlator,FnJTC)结构,给出了数学推导过程,并通过计算机模拟验证了可行性及其与传统相关器所不同的相关特性。在相关过程第一阶段中,菲涅耳联合变换相关器对输入的联合图像作菲涅耳变换,代替了传统联合变换相关器(JTC)的傅里叶变换。与传统相关器相比,菲涅耳联合变换相关器是空变系统,相关峰值依赖于输入参考图像与目标图像的相似性、两图像之间的相对位置及参考图像(或目标图像)的线性相位调制。 相似文献
4.
5.
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
6.
实时光电混合联合变换相关器单元的实验研究 总被引:11,自引:3,他引:8
本文根据联合变换相关的原理,提出了一种实时光电混合联合变换相关器,它采用一个液晶光阀作为输入器件,用另一个液晶光阀记录和显示联合功率谱,所给出的实验结果证实了该系统设计及性能分析的正确性。 相似文献
7.
光电混合变换相关器在体视测距中的应用 总被引:1,自引:0,他引:1
本文研究了体视测距系统的图像联合变换相关原理,推导出利用像联合变换相关测量目标距离的公式。同时,本文表明把光电混合联合变换相关器用于体视测距系统的原理装置和测距实验。 相似文献
8.
9.
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
10.
基于微分滤波的联合变换相关 总被引:4,自引:1,他引:3
分析了微分滤波对联合变换功率谱的影响,得到了一种称之为功率谱形式的微分滤波器,该滤波器的滤波函数为一实数并且有一定的特点,因此很容易制得,计算机模拟表明,功率谱微分滤波联合变换相关器在相关峰值,旁瓣比,半宽度等方面比一般联合变换相关器有显著的改善,可以大大提高相关图像识别的可靠性,文中给出了实验结果,与模拟计算结果吻合,引入一个新参数可以更好地描述相关图像识别中的相关性。 相似文献
11.
We present an alternative technique to enhance the discrimination performance in a JTC architecture, employed as a validation procedure. We define as complex objects those amplitude objects bonded to random phase masks. When using complex objects as reference inputs in a JTC optical validation system, correlation peak intensity and correlation peak shape become simultaneous key parameters to increase the discrimination ability of the system. Simulation results, comparing amplitude-only objects versus complex objects as inputs to the system, reveal the validity of our approach and show the sensitivity of the JTC architecture to the additional phase structures. 相似文献
12.
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
13.
In this work we study the joint transform correlator (JTC) optical encryption setup through the Wigner function. We found analytical expressions for the spatial and spatial frequency extent of the encrypted signal. Since the JTC is inherently an asymmetrical optical system, different expressions were found for each spatial axis and for their associated spatial frequency axes. We also compare these results with the dual random phase encoding technique. Finally, we found an analytical expression for the minimum separation between channels that avoids crosstalk in a wavelength multiplexing JTC architecture. 相似文献
14.
15.
实时高效联合变换相关器 总被引:13,自引:0,他引:13
提出一种利用光学波分复用器实现实时高效联合变换相关的方案。通过计算机控制把输入面分为多个大小相等的窗口,分别写入参考与目标图像,利用光学波分复用器于相关系统中,使对应不同窗口的读出光学信息在第一个焦面上形成联合功率谱阵列,在输出面上可以实时地获得增强了相关信号。 相似文献
16.
17.
We propose a Fourier-plane encryption technique based on a joint transform correlator (JTC). The technique is based on removing
the effect of phase terms in JTC and the auto-correlation terms contribute to reconstructing the original image. Computer
simulations and optical experiments show the proposed method is very useful for JTC architecture. 相似文献
18.
为了解决在联合变换相关器上无法识别复杂背景下畸变目标(目标的平面内旋转或尺寸改变)的问题,对其应用最大平均相关高度滤波算法进行畸变目标识别.首先在频域内优化最大平均相关高度滤波器的三个性能控制参量|然后将优化好的最大平均相关高度频域滤波器映射到物空间,得到最大平均相关高度参考模板.作为实例,本文对复杂背景下的军舰和汽车目标进行了光学识别实验,结果表明,当滤波器的控制参量为γ=1,α=0,β=0.1时,得到的MACH参考模板最为清晰,目标产生的相关峰最为尖锐明亮.通过这种方法,在联合变换相关器上能够得到的比例畸变容差为28%,旋转畸变容差为20°,对于超出上述畸变容差范围的目标,相关峰强度逐步减弱,但部分仍然可以识别.改进后的MACH滤波器在畸变目标的探测领域具有很强的优势和良好的应用前景. 相似文献