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Infrared thermal imager is widely used as target detection, search and tracking system due to its super night vision capability. The traditional thermal imager will cause column noise and serious image degradation due to temperature change, which will affect the observation effect. Therefore, it is necessary to carry out non-uniformity correction by the baffle (or shutter). However, in the process of shutter correction, there will be a short time for the search and tracking equipment to fail to work, which is easy to cause target loss. At present, all search and tracking systems require the installation of a continuously working infrared thermal imager without shutter. In order to realize the non-uniformity correction technology of infrared thermal imaging without shutter, a fast correction method for image gradient optimization based on noise template is proposed in this paper. Due to the special manufacturing process of the detector, when the temperature of the detector changes, the output image will produce vertical stripes with regular shapes. The noise patterns obtained at different temperatures are linearly related. Therefore, there is a noise model M, which makes the noise matrix at any temperature can be expressed as the product of M and a constant k (k is related to the detector Temperature K). The fringe noise of the image is quantified by detecting the sum of the absolute values of the transverse gradients of the image, and the non-uniformity correction without shutter is realized by adjusting the parameters so that the sum of the absolute values of the transverse gradients is minimized. This method can not only compensate temperature drift, but also replace the shutter to realize one-point correction, which reduces the power consumption of the whole machine and improves the reliability. There is no need for complicated calibration work in High and low temperature test chamber. It is not even necessary to record the current detector working temperature in real time for calculation. This method is simple in structure and easy to implement. The practical application proves that the infrared thermal imaging system has clear imaging. The effect is excellent.
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