Research On Infrared Dim Target Detection Under Complex Background

The detection and tracking algorithm of dim-small infrared targets has always been key technology in photoelectric detection and tracking system. The signal-to-noise ratio is sufficiently low due to the large detection range, no information content of targets signature can be used. Therefore, how dim point target scan be robustly detected and tracked under complex aerial background have become the more realistic and challenging research topics.Around detection of dim-small infrared targets in complex aerial background, the thesis analyzes the characters of infrared images, and makes progress with the key technology in complex background suppression, energy enhancement of weak targets and target detection.The main content of the thesis includes:(1) The author makes the model of infrared image. Verify the model though analyzing three basic characteristics of actual infrared small-dim target images, including of target, noise and background.(2) Infrared image preprocessing. Firstly, the author introduces the frequently-used algorithms of infrared image preprocessing based on spatial filter, temporal filter and transformation filter. Detailed analysis is focused on the median filter method and morphology filter method. An improved mathematical morphology filter is applied to Infrared image preprocessing. And further, finish processing the filtering image by the method of local maximum segmentation.(3) After suppressing the background, the gray-scale contrast of targets is still inconspicuous, and there are many noises in infrared images, which is not conduction to get the dim-small targets accurately.We analyze Higher-order correlation based algorithm for dim signal detecting in multi-frame image sequences. Considering the property of target motion, twelve Gaussian templates are built to model target position in the next frame, a new small moving target detection algorithm can also suppress the gauss noises and perfectly improve the signal-to-noise ratio of the infrared images.(4) Small moving target detected method in image sequences is demonstrated. We analyze dynamic programming based algorithm for dim signal detecting in multi-frame image sequences. And detect the Small-dim target based on the dynamic programming.