Research On Enhancement Technology Of Correlation Peaks With JTC For Targets With Low Contrast

Optical correlation detection and recognition is to process all sampling points at the same time and realize Fourier transform of image signals with light speed. Modern optical test technology is combined with modern detecting devices in this paper. Optoelectronic hybrid joint transform correlator is developed successfully and detection, real-time tracking, automatic recognition are realized with high location accuracy. However, real targets have relative complex background, low contrast and insufficient brightness, which usually lead to decrease the ability of target detection and recognition and even miss the target. Therefore, one of the key technologies is to implement image processing of object image and power spectrum image to improve recognition rate of targets.To enhance the contrast of correlation peaks, Mexico-hat wavelet transform is adopted in power spectrum plane, with which noise information of joint transform power spectrum is suppressed successfully. Useful information is increased and the contrast of correlation peaks is also strengthened.As to the static targets recognition, many methods are adopted in the object plane to suppress the noise interference of background effectively, improve contrast of most correlation peaks and strengthen correlation recognition ability of static targets in cluttered background with low contrast. The methods include contrast stretching, edge detection by Gauss wavelet modulus maximum value, combination of edge detection by Gauss wavelet with mathematical morphology, combination of mathematical morphology with threshold processing and edge detection by improved Robert operator.As to targets on water with low contrast, experiments show the energy of correlation peaks are stronger with the combination method of mathematical morphology and edge detection by Gauss than the other methods. Correspondingly, background noise is weaker and contrast of correlation peaks is also better.As to targets on land with low contrast, experiments show the energy of correlation peaks are stronger with the method of edge detection by improved Robert operator and combination method of mathematical morphology and edge detection by Gauss wavelet. Thus, background noise is weaker and contrast of correlation peaks is also better.As to dynamic targets, the processing method of automatic threshold in object plane is researched, with which background noise is filtered out effectively in object plane and contrast of correlation peaks is also strengthened. Therefore, detection and recognition of moving targets with cluttered background and low contrast is realized successfully by optoelectronid hybrid joint transform correlaor.