“…HR images have higher pixel densities and finer details than LR images. Image SR has been proved to be of great significance in many applications, such as video surveillance [21,22,23], ultra-high definition TV [24], low-resolution face recognition [25,26,27,28,29] and remote sensing imaging [30,31]. Benefiting from its broad application prospects, SR has attracted huge interest, and currently is one of the most active research topics in image processing and computer vision.…”