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 202.69×106 to 2.32×106, and average gradient can be decreased from 5.08×10-1 to 2.26×10-1 after the smear correction.