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Fusion of infrared (IR) and visible sensor images is the widely applied. The registration is the basis for sensor fusion and fusion methods are very sensitive to the level of registration accuracy. However, the different imaging systems of the both lead to quite different image characteristics in a same scene and significant misalignment due to differences in field of view, lens distortion and other camera characteristics. So that, the registering accurately the both of sensor images is very challenging. A method to improve the accuracy of image registration is proposed in this paper. The method is based a self-designed long-wave IR/visible dual-band imaging system for capturing simultaneously both of images, which is not only with synchronous focusing and optical registration as much as possible, but also with a sliding potentiometer that record the voltage corresponding to the focusing distance. At first, an affine transformation of the registration at several different distances is acquired with two calibration board images captured self-designed calibration board by the dual-band imaging system. Then, the affine transformation matrices corresponding to the several finite distance are interpolated to obtain more affine transformation matrices within a certain distance, and an accurate look-up table is established. Last, when the dual-band imaging system is working, the current focal length is read out according to the sliding potentiometer in the system, and then the corresponding affine transformation matrix is searched for image registration. The proposed method is evaluated by comparing the deviation of the corresponding feature point coordinates on both of calibration board images before and after registration. Experimental results show that the proposed method can improve the registration accuracy of IR and visible images at different distances.
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