Boosting Diffusion Guidance via Learning Degradation-Aware Models for Blind Super Resolution

Recently diffusion-based blind super-resolution (SR) methods have shown great ability to generate high-resolution images with abundant high-frequency detail but the detail is often achieved at the expense of fidelity. Meanwhile another line of research focusing on rectifying the reverse process of diffusion models (i.e. diffusion guidance) has demonstrated the power to generate high-fidelity results for non-blind SR. However these methods rely on known degradation kernels making them difficult to apply to blind SR. To address these issues we introduce degradation-aware models that can be integrated into the diffusion guidance framework eliminating the need to know degradation kernels. Additionally we propose two novel techniques--input perturbation and guidance scalar--to further improve our performance. Extensive experimental results show that our proposed method has superior performance over state-of-the-art methods on blind SR benchmarks.