Components-balanced guided diffusion for retinex-based low-light image enhancement
摘要
Low-light conditions often degrade image quality, posing challenges in various multimedia and computer vision applications. Based on the Retinex theory, we introduce components-balanced guided diffusion (CBGD), a unibranch Retinex-diffusion framework that regards the normal-light condition as the balanced state of reflectance-illumination components. The proposed CBGD concatenates reflectance and illumination into a multi-channel input and performs a single diffusion process, enforcing shared, synergistic corrections across both components at every timestep. To direct the reverse process toward the normal-light state, we design a sampling-based relighting guidance to provide low-light-to-normal-light supervision. Furthermore, we introduce multiple losses that constrain reflectance, illumination, and their recomposed image jointly. Extensive experiments on 10 public datasets demonstrate state-of-the-art performance, with significant improvements in LPIPS, PSNR, SSIM, and NIQE metrics. When applied as preprocessing for low-light object detection, CBGD significantly boosts detection accuracy, confirming its practical utility. The code and results are available at: https://github.com/Klawens/CBGD.