1. Introduction
Super-resolution is the problem of generating a high-resolution image from one or more low-resolution images. While most methods have been proposed for super-resolution based on multiple low-resolution images of the same scene (e.g., [2], [6], [8], [2] [2]), the focus of this paper is on generating a high-resolution image from a single low-resolution image, with the help of a set of one or more training images from scenes of the same or different types. We refer to this as the single-image super-resolution problem.