Spatial Quality Enhancement for Wide View Angle Images: A Sensor-Specific Preprocessing Algorithm Case Study on FY-3D MERSI-II

In recent decades, medium-resolution satellites have played a pivotal role in ecosystem research, providing global daily coverage. The Moderate-Resolution Spectral Imager (MERSI), a key component of Fengyun-3 (FY-3) series, exhibits excellent data continuity over three generations, delivering large-scale spatial-continuous documents. However, images from sensors with wide view angles often exhibit considerable artifacts due to restriction of multidetector parallel scanning system and multi-interferences from space. Furthermore, MERSI introduces known observation redundancy across pixels and tracks, presenting significant yet untapped potential for image quality optimization and restoration from Level-1 (L1) to downstream products. We proposed a spatial quality enhancement (SPQE) algorithm for MERSI-like sensors. It has demonstrated effectiveness in generating detailed spatial information images without artifacts while retaining spectral information with four main procedures: 1) atmospheric correction inspired by Moderate-Resolution Imaging Spectroradiometer (MODIS); 2) optimization of geolocation sample methods through linear extrapolation, elimination of bow-tie effect through empirical screening; 3) utilization of observation redundancy from adjacent pixels through a restoration algorithm based on Thomas method; and 4) exploitation of observation redundancy from adjacent tracks via relative registration and information stack sampling. To illustrate the effectiveness and robustness of SPQE, the widely used MERSI-II images are tested. Examples of SPQE-derived surface reflectance (SR) imagery across global scenarios are provided. We evaluate the potential effect of SPQE on reflectance and ecological applications. Extensive validation demonstrates that downstream products generated by SPQE-derived images exhibit a stronger correlation with classic products and public datasets compared to nonenhanced images. Given its performance and versatility, we anticipate the widespread use of SPQE for similar sensors.