Study On Infrared Target Detection And Recognition Technology Of Infrared Search System

Infrared Search Systems (IRSS) are electro-optical detectors which detect, recognize and track targets by receiving their Infrared emission passively. The IRSS which, either working alone or as part of radar surveillance suite, search and scout military targets, can provide target information to fire control system of weapon platforms. In general, IRSS has passive detection and invisibility, high resolving ability, fine anti-jamming ability, small volume, lightweight and high maneuverability. For these advantages, IRSS becomes an important component of the nation defense system, and obtains wide attention and energetic cooperation in recent years. As for the real weapon systems, how to make the best of IR target detection techniques to increase the distance of target detection and to obtain the related information about the invading targets, have become important factors to decide the victory or defeat of modern warfare. But when target is far away from sensors, the target is point-like and the image SNR is very low. The target signal amplitude is weak relative to the noise amplitude and lacks distance information. Therefore, comparing with other topics in the field of IR target detection and tracking, how small targets can be robustly detected and tracked under complex backgrounds have become the more realistic and challenging research topics.The main contents of this study was based on the Infrared focal plane array (IRFPA), including the research of the infrared radiation and transmission characteristics; analyzing the imaging model of the target and the influence of the clutter and noise; study of the infrared background suppression technology. Research and compare a series of background suppression algorithms based on this platform, and improve these algorithms to fit for this platform; further study of the target detection and track technology. Thus, the two sub-topics in the field of small target detection and tracking, background suppression and small target detection are realized in an integrated adaptive framework.This paper analyze the infrared radiation characteristics of the target (aircraft, cruise missiles), and discuss the atmospheric transmission characteristic. This all provide the theoretical basis to choose the infrared band and system parameter. The Point Scattering Function (PSF) of degradation model images blurred by IRFPA s' rotations is presented, and analyze the temporal and spatial distribution of noise and clutter.In the background suppression, studies and compare the existing algorithms, and these algorithms are improved to apply for IRSS based on IRFPA. Based on the analysis of these algorithms, this paper proposed a series of algorithms based on spatial and temporal characteristic of the target in the IRSS based on IRFPA. They are Minimum Rows Difference Filter, which is based on the spatial characteristic of target in single frame, Local Area Order statistics filter, based on the target's shape similarity, a multi-scale filter based on the wavelet transform, and the algorithm based on Optical Flow Histogram and its simplified algorithm: frame matching filter. Through experiments result, each algorithm's characteristics and the application conditions is compared and analyzed.In order to advance the detection ratio of dim target in clutter background, this paper proposed an adaptive background adjusting algorithm. A detection method based on synthesizing different algorithms is advanced. This method synthesizes the detection results of algorithms, and decides the grade of each target. Experiments show that this method enhances the target detection ratio, and reduces the false alarm, caused by clutter and noise.This paper designs a multiple hypotheses tracking scheme for IRSS based on IRFPA. The presented multi-target tracking (MTT) method adopts Kalman filter to predict new position of target, and a complete algorithm framework is brought forward for track initiation, track maintaining and track ending. In track maintaining, target's position and mean gray level are taken into count, and a new data association technique based on multiple target characters is investigated. An emulator of dim and small targets detection and tracking is designed to confirm validity of methods. Results show that algorithms of target detection and tracking in IR image sequences have high clutter suppression ability, anti-target-missing ability and significant real-time processing ability.Designed and implemented signal processing systems based on FPGA + DSP. According to the proposed target detection and tracking algorithm and theory, the algorithms is improved to easy to implement in this processing systems. A large number of experiments show that algorithms proposed in this paper are efficient and practical.