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The exposure mechanism of the rolling shutter CMOS detector is elaborated, which has the characteristics of nonsimultaneous exposure of each line of pixels. On this basis, the effects of image motion on imaging are analyzed, including image blur and image distortion, and thus obtaining the limit range of exposure time setting. According to the working mechanism of the rolling shutter, the forward coordinate transformation of image distortion and its distortion results are clarified. Then the distortion correction method and theoretical model are deduced in reverse, including two steps of coordinate transformation and resampling. Simulation results show that the method can effectively correct distortion. Finally, the contrast of the corrected images is compared when the rolling direction and the image motion are in different directions. The results show that when the rolling direction is perpendicular to the image motion, the highest average contrast can be obtained, but with the maximum uncertainty. When the rolling direction is in the same direction as the image motion, the average contrast is the lowest, but with the minimum uncertainty. Considering comprehensively the complexity of the image distortion correction algorithm and the average contrast from the image output, it is an optimal choice to set the CMOS detector's rolling direction perpendicular to the image motion.
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