I. Introduction
Image super-resolution (SR) refers to the task of upscaling a given low-resolution (LR) image with coarse details to a high-resolution (HR) image with refined details and enhanced visual quality. Image super-resolution is often associated to other terminologies such as upsampling, interpolation, image scaling, zooming and enlargement. It has been proved that upsampling an image via super-resolution methods can largely refine the amount of available information and thus lead to accurate and robust vision-based machine learning systems [1]. As a result, super-resolution methods have achieved cross domain acceptability and enjoy a wide range of applications such as medical imaging, surveillance and security, aerial imaging, compressed image/video enhancement, action recog-nition, remote sensing, astronomical images, forensics, pose estimation, fingerprint and gait recognition and many more. Apart from improving the perceptual quality, it also helps in other deep learning based computer vision tasks such as object detection, image segmentation.