基于时域偏移量的红外非均匀校正算法

Infrared Non-Uniformity Correction Algorithm Based on Time-Domain Offset

  • 摘要: 受限于制冷型红外探测器的材料特性以及制作工艺,红外图像普遍存在像元间的不一致性,红外图像的非均匀性会严重影响在轨成像效果。尤其在均匀背景下的点目标探测,会提高在轨探测的虚警率。两点法校正是一种典型的红外遥感器在轨图像非均匀性处理手段,从一定程度上抑制了图像的非均匀性。两点法的图像处理机理就决定了这种图像处理方法的校正效果不仅与相机的成像参数相关,在时域上还与探测器的工作温度相关。因此制冷型红外探测器的光学遥感器在每次成像任务中成像参数即使固定不变,仍然需要通过获取星上定标器的内定标图像实时计算校正系数,从而保证红外图像的非均性得到抑制。以线阵推扫中波红外遥感器为实验对象,提出一种时域自适应校正算法,在两点法校正的基础上引入时域上的响应修正量,纠正工作温度变化对非均匀校正系数时效性的影响。目前此算法已应用于在轨光学遥感器,该算法的引入有效减小了在轨定标的频次,增强了红外通道应急成像任务的处理能力。

     

    Abstract: Given the material characteristics and manufacturing process of refrigerated infrared detectors, pixel inconsistency is common in infrared images. This non-uniformity of infrared images can significantly degrade the quality of on-orbit imaging. In particular, detecting point targets against a uniform background becomes more challenging, often increasing the false alarm rate during on-orbit detection. The two-point correction method is a typical processing method for addressing image in-homogeneity in infrared remote senor data in orbit. This method can effectively restrain image in-homogeneity to a certain extent. However, the correction effect of this image processing method only depends on imaging parameters of the camera but also on the working temperature of the detector in the time domain. Therefore, even if the imaging parameters of the optical remote sensor of the refrigerated infrared detector are fixed in each imaging mission, the correction coefficients must still be calculated in real time. This is achieved by obtaining internal calibration images of the on-board calibrator, thereby ensuring that the heterogeneity of the infrared image is suppressed. Based on a linear push-sweep mid-wave infrared remote sensing camera, an adaptive time-domain correction algorithm in is proposed. Currently, the algorithm has already been deployed in on-orbit optical remote sensors, where it effectively reduces the frequency of in-orbit calibrations and enhances the processing capability of emergency imaging in the infrared exterior passage way.

     

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