I. Introduction
The rapid development of modern aerospace technology has advanced the wide use of remote sensing images in remote sensing applications. Nonetheless, for some highly accurate remote sensing image interpretation assignments, such as military target detection [1], fine-grained classification [2], object tracking [3], and detailed environment monitoring [4], the spatial resolution of the optical sensors cannot meet the accuracy requirements, and becomes the limitation in image interpretation. Even though satellites with the most advanced technology can provide a resolution within a square meter, the high costs of this acquisition technology hinders its application, then single image super-resolution (SISR) technology has been widely studied in depth to improve the spatial resolution of remote sensing imagery [5], [6]. SISR algorithm aims to generate high-resolution (HR) images from a low-resolution (LR) image input by yielding more detailed information and improving the quality of images [7]. Due to the wide use of SISR, there is increasing interest in HR images, especially in the remote sensing field.