| Electronic image stabilization is a new technology to stabilize video image sequence. Because of its advantages of high image stabilizing precision, compact size, lightweight, low power consumption and reasonable price, the electronic image stabilization has become a focus of study competition among developed countries in west of the world. Especially it is applied to men-manipulative weaponry equip. Because the air-borne imaging system is required a far acting distance and the focal length of its optical system is long. Influenced by the unsteady or moving platform mounted on plane, the change between the frames of image sequence is more. Problems of image fuzziness and instability tend to be striking out, which becomes a bottleneck restricting the air-borne reconnaissance, collimation, evaluating beat effect. This thesis, supported by the Youth Innovation Fund of Chinese Academy of Science, has carried out an intensive study of the technique of air-borne electronic image stabilization, and put forward the effective method for realizing stabilization of the air-borne video image.This thesis analyzes the blurring cause of image sequences taken by airborne imaging sensors and proposes the necessity of electronic image stabilization for the airborne imaging system. It expatiates principle and method of electronic image stabilization in detail and discus key technique of realization. Based on study for several typical algorithms of motion vector estimation adopted by overseas electronic image stabilization system, the principle of choosing motion estimation algorithm in designing system has been put forward.The implement of gray projection matching algorithms applied to stabilization of image sequences taken by airborne imaging sensor is introduced and the main factors to affect the accuracy of algorithm have been analyzed according to characteristic of airborne imaging. The efficient preprocessing method of image sequences is proposed to help to increase robusticity and improve accuracy of projection algorithm.The software has been worked out with VC++, which can realized "real-time" processing to airborne image sequences. At this settings the system can process 25 frames per second, and the RMSE is smaller than 0.325.The necessity and possibility to estimate and compensate camera rotation in the long focus imaging system is proposed according to characteristics of airborne imaging system. And choosing some points that have great gray levels as image characteristic toestimate motion is also given. In order to guarantee the validity of this algorithm, firstly the characteristic of an image is extracted, then the frame is divided into several blocks. In each block feature points are chosen to estimate the motion vectors according to certain scanning order. During the feature point matching, in order to reduce the computation complexity and speed matching, a multi-resolution strategy is adopted. The simulation results show validity of presented method for compensating the rotation motion.Compensation method of motion among the frames is also an important factor to affect the stability of image sequence, if the image sequence is compensated directly with the acquired movement vectors, it will feel the jumping of frame. In the paper, the parameter to compensate for the current image can be determined by average value filtering and have been applied to given motion model to stabilize the image stream. It can realize smoothly processing the image sequences to assure its stabilization.A lot of image stabilization experiments have been carried out with the video image sequence taken by airborne imaging system and the stabilization effect is evaluated. The simulation and experimental results demonstrated that this method proposed in this thesis is feasible.
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