共查询到18条相似文献,搜索用时 437 毫秒
1.
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
2.
从分数傅里叶变换(FRFT)的定义出发,理论分析了联合分数变换相关器(JFRTC)的分数相关特性.从所得JFRTC的数学表达式中可以看出,将FRFT应用到联合变换相关器(JTC)中得到的JFRTC具有与传统JTC不同的性质.对于传统JTC,一旦输入平面上参考图像与目标图像之间的距离给定,相关输出峰的位置即确定,而JFRTC的相关输出峰的位置则可以由分数级次p1和p2来自由调节,这个特性在实际模式识别中非常有用.另一方面,JFRTC的相关输出峰值在大多数情况下低于传统JTC的相关峰值,却是JFRTC的一大缺点.最后,从FRFT的比例性质出发,给出了FRFT谱畸变不变的实现条件,并由此预言了JFRTC畸变不变模式识别的功能. 相似文献
3.
4.
5.
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
6.
7.
8.
利用Wigner分布函数(WDF)方法,对光束的分数傅里叶变换特性进行了研究.以厄米 高斯(H G)光束为例,导出了H G光束在分数傅里叶变换面上光强分布的解析公式和H G光束在分数傅里叶变换面上束宽的解析计算公式.通过数值计算研究了H G光束光强随分数傅里叶变换阶数变化的规律.研究表明:选取适当的分数傅里叶变换阶数p,在x,y方向可以得到相等束宽的对称光强分布.
关键词:
Wigner分布函数
厄米 高斯(H G)光束
分数傅里叶变换 相似文献
9.
10.
11.
A displacement measurement technology based on joint fractional Fourier transform is firstly proposed. Contrast to conventional displacement measurement based on joint Fourier transform correlator, the position of cross correlation peak in the proposed technology could be fixed arbitrarily according to the order of fractional Fourier transform. The optical setup in the proposed technology is more flexible and easier to implement. Simulation and experiment results are given out to verify the analysis. 相似文献
12.
In order to utilize the space of an input plane efficiently and make the optical structure more flexible, an image displacement measurement based on phase-encoded reference joint fractional transform correlator (PER-JFrTC) is proposed. We use a random phase mask to encode the reference image and overlay it with the target image forming the input image. Joint power spectrum (JPS) of the input image is obtained by Fourier transform and the resultant is encoded by the same phase mask. Then a fractional Fourier transform with an order p is applied to the phase-encoded JPS (PJPS), resulting in a correlation output with a sharp cross-correlation peak, which includes the displacement information between the reference and the target image. Contrast to displacement measurement based on traditional joint transform correlator (JTC), PER-JFrTC can use the space of the input plane efficiently and reduces the influence of the auto-correlation. Also the position of cross-correlation peak can be fixed arbitrarily according to the fractional order p as well as the optical set-up can be more flexible and easier to implement. Results based on digital computation show that PER-JFrTC could detect the displacement accurately and verify our proposal. A possible optical set-up is suggested. 相似文献
13.
Based on the conventional correlation and fractional correlation, the extended fractional correlation (EFC) is presented. And based on the configuration of the nonconventional joint transform correlator, we propose the joint extended fractional Fourier transform correlator (JEFRTC). The properties of the extended fractional cross correlation peak (EFCCP) in theory are analyzed. A sound conclusion is drawn that the width of EFCCP is narrower than that of fractional correlation peak under some conditions. This JEFRTC can permit lower precision of the systemic parameters when implemented with optical configuration. That will improve correlator’s character discriminability. 相似文献
14.
An extended fractional wavelet joint transform correlator is implemented for real-time target recognition applications. The real-time input scene captured using a charge-coupled device camera along with the reference image is fractional Fourier transformed. The obtained joint power spectrum is multiplied by an appropriately scaled wavelet filter and the resultant function is differentiated. The application of wavelet filter enhances the correlation outputs and differential processing of wavelet-filtered joint power spectrum improves the detection efficiency by reducing the zero-order spectra. Targets with Gaussian and speckle noise have also been used to check the correlation output. The performance metrics: correlation peak intensity, peak-to-correlation energy, peak-to-sidelobe ratio and signal to clutter ratio have been calculated. The experimental results are presented in support of the proposed idea. 相似文献
15.
16.
A new system of multi-channel single-output joint fractional Fourier transform correlator (JFRTC) for color pattern recognition is proposed based on the conventional system of multi-channel single-output joint transform correlator (JTC). The theoretical analysis and optical experiments are performed. With this method, one can obtain three correlation peaks at the output plane which show a pair of desired cross-correlation peaks and one auto-correlation peak. In comparison, the conventional system leads to more correlation peaks playing a noise role in color pattern recognition. 相似文献
17.
Wavelet-modified fringe-adjusted joint transform correlator 总被引:1,自引:1,他引:0
Alpana Bhagatji Naveen K. Nishchal Arun K. Gupta B.P. Tyagi 《Optics & Laser Technology》2008,40(1):99-112
In this paper, we implement a wavelet-modified fringe-adjusted joint transform correlator (JTC) for real-time target recognition applications. In real-time situation the input scene is captured using a charge-coupled device (CCD) camera. The obtained joint power spectrum is multiplied by a pre-synthesized fringe-adjusted filter and the resultant function is processed with an appropriately scaled wavelet filter. Three performance measure parameters: correlation peak intensity, peak-to-sidelobe ratio, and signal-to-clutter ratio have been calculated for fringe-adjusted joint transform correlator (FJTC) and wavelet-modified fringe-adjusted joint transform correlator (WFJTC). The WFJTC has been found to yield better results in comparison to conventional FJTC. To suppress the undesired strong dc, the resultant function is differentiated. Differential processing wavelet-modified fringe-adjusted joint power spectrum removes the zero-order spectra and hence improves the detection efficiency. To focus the correlation terms in different planes in order to capture one of the desired autocorrelation peaks and discard the strong dc and another autocorrelation peak, chirp-encoding technique has also been applied. Targets with Gaussian and speckle noise have also been used to check the correlation outputs. Computer simulation and experimental results are presented. 相似文献
18.
Abdullah Bal 《Optik》2006,117(1):1-8
Subband multiresolution technique presents decomposition and reconstruction properties for 2D images using multichannel spatial filtering. Each subband image represents multiresolution of the input image. In this paper, optic subband multiresolution architecture is proposed based on multi-object phase-only joint transform correlator (JTC). Multichannel filtering is realized using multi-object input joint image that includes bipolar data. The bipolar data (containing positive, zero and negative values) is encoded by phase in the input and Fourier planes of the phase-only JTC. For image decomposition and reconstruction, two optoelectronic subband multiresolution architectures have been developed. Each architecture has been tested using a simulation program. 相似文献