多角度偏振成像仪遥感图像太阳耀斑区的拖尾校正方法

为了有效校正星载偏振相机成像时太阳耀斑区产生的拖尾,以高分五号卫星多角度偏振成像仪为例,结合多角度偏振成像仪在轨成像特点,理论分析了图像获取过程中拖尾产生的机理.建立了光斑区不含饱和像元情况下能够有效对漏光拖尾进行校正的矩阵法与暗行法校正模型,以及光斑区全像元饱和情况下结合矩阵法与暗行法估计光斑区饱和像元强度的遗留拖尾校正模型,该算法充分考虑了强光饱和条件下太阳耀斑区产生的漏光拖尾与遗留拖尾.利用实验室积分球光源成像光斑模拟在轨运行时遥感图像太阳耀斑开展拖尾校正方法可行性验证实验.实验结果表明,该方法不仅能有效去除图像中的拖尾噪声,提高图像质量,而且能够对光斑饱和像元强度进行有效估计.最后,分析多角度偏振成像仪在轨成像图中耀斑区拖尾对其辐亮度测量精度的影响,分析结果表明,拖尾校正前后,灰度方差由202.69×10^6下降至2.32×10^6,平均梯度由5.08×10^-1下降至2.26×10^-1.

Calibration Method of Smear in the Sun Glint Region of Directional Polarization Camera Remote Sensing Images

In order to effectively correct smears in the sun glint produced by spaceborne polarization camera imaging,this paper takes the GF-5 satellite directional polarization camera as an example and combines with imaging characteristics of directional polarization camera on orbit to theoretically analyze the generating mechanism of smears in the process of image acquisition.It sets up a matrix method calibration model and a dark line method calibration model both of which can effectively correct the light leakage smear under the circumstances of without any saturated pixel in the flare region.And it sets up a legacy smear calibration model based on a combination of the matrix method and dark line method under the circumstances of full pixel saturation in the flare region to estimate saturated pixel intensity in the flare region.This algorithm fully considers the leakage smear and legacy smear produced in the sun glint under the circumstances of intense light saturation.The feasibility of this smear correction method is verified by using spots of integrating sphere light source imaging in the laboratory to simulate solar flares in remote sensing images of directional polarization camera when it works on orbit.The experimental results show that this method can not only effectively remove smear noise in images and improve image quality but also effectively estimate spot saturation pixel intensity.In the end,this paper analyzes the influence of the flare region smear in directional polarization camera on-orbit images on radiance measurement accuracy of directional polarization camera.Analysis results show that gray variance can be decreased from 202.69×10^6 to 2.32×10^6,and average gradient can be decreased from 5.08×10^-1 to 2.26×10^-1 after the smear correction.