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排序方式: 共有203条查询结果,搜索用时 265 毫秒
21.
黄金分割法是一种快速搜索函数极值的优化设计方法.研究了它在快速在线极性相关器中的应用,详细讨论了极性相关函数极值搜索的黄金分割设计方法.采用8031单片微机构成极性相关器,黄金分割法的应用,使得完成一次相关分析的时间缩短到1秒以内. 相似文献
22.
Effects of threshold value on detection performance of the modified amplitude-modulated joint transform correlator are quantitatively studied using computer simulation. Fingerprint and human face images are used as test scenes in the presence of noise and a contrast difference. Simulation results demonstrate that this correlator improves detection performance for both types of image used, but moreso for human face images. Optimal detection of low-contrast human face images obscured by strong noise can be obtained by selecting an appropriate threshold value. 相似文献
23.
Arturo Carnicer Santiago Vallmitjana JosRamn de F. Moneo Ignacio Juvells 《Optics Communications》1996,130(4-6):327-336
An original method to detect images in defocused scenes by means of a binary joint transform correlation is presented. Defocused images are described in frequency domain as the product between the Fourier transform of the in-focus scene by the optical transfer function of the imaging lens. This function, which presents positive and negative values, introduces sign errors in the joint power spectrum. The goal of this study is to detect the sign of the optical transfer function starting from the defocused image by means of a digital algorithm. Information provided by the algorithm allows to compensate the sign errors in the binary joint power spectrum and to obtain invariant correlations with respect to defocusing. Theoretical analysis and digital experiments to test the procedure are provided. 相似文献
24.
When real time optical pattern recognition is carried out by means of spatial light modulators, a practical situation may arise in which the size of the Fourier transform and the intensity of the light source are fixed. Then, provided the input scene and the size of the spatial light modulator allow it, an interesting possibility for improving the overall intensity in the Fourier plane is the replication of the scene, either along a regular lattice structure or a random replication. In this work we analyse the usefulness of these methods, both to obtain diffraction images or cross-correlation between images in a joint transform correlator. 相似文献
25.
OpticalCorrelatorandPhotorefractiveTwo-waveMixingBasedNeuralRecongnition¥FUXiaoli;LIYulin(Xi'anInstituteofOpticsandFinsMechan... 相似文献
26.
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
27.
28.
K. S. Dharmsaktu Arvind Kumar Renu Tripathi K. Singh 《Optics and Lasers in Engineering》2000,34(3):191
A technique has been proposed to analyze small in-plane component of vibrations by measuring the fringe shift, and analysing the correlation output of captured vibrating Young's fringes with a photorefractive correlator. Fringes are formed due to interference between the reconstructed speckled beam recorded for stationary object beam, and vibrated speckled beam transmitting through a BaTiO3 crystal after introducing a small shift in the diffuser position. The correlation peak intensity is affected due to mismatch of vibrations between two piezo-mirrors in the object beam. High correlation output gives an indication of the frequency matching of known reference and unknown vibrations, thus giving information on the frequency of vibration. Vibration amplitudes of the order of a wavelength of light have been measured by counting the number of fringes passing past a line in the observation plane. 相似文献
29.
光学图像识别相关器的MATLAB仿真 总被引:5,自引:1,他引:4
利用MATLAB提供的图像处理函数来模拟光学图像识别相关器对图像的识别,得到较好的仿真结果。 相似文献
30.