1 Introduction
As a fundamental problem in computer vision [1], super-resolution has been a popular research topic and has direct or indirect applications in many fields. After years of development, the overall approach of super-resolution methods can usually be divided into three categories namely interpolation-based methods, model-based methods, and deep learning-based methods, where deep learning-based methods tend to have better results compared to the first two, and deep learning-based methods usually have better results in terms of feature representation as well as stronger inference capabilities and easier to implement end-to-end training frameworks. As a result, deep learning has been dominant in solving super-resolution problems for the past many years. However, most of these methods rely heavily on fixed and known downsampling methods [6], [8], [9], [10], and this limitation may hinder the performance of these methods when applied to realistic scenarios with unknown or uncertain degradation patterns. To address this challenge, researchers have proposed blind super-resolution (SR) methods designed to handle unknown or uncertain degenerate patterns.