TS-Diff: Two-Stage Diffusion Model for Low-Light RAW Image Enhancement

TL;DR

TS-Diff introduces a two-stage diffusion approach with camera feature integration and a new dataset to significantly improve low-light RAW image enhancement, ensuring better denoising, generalization, and color accuracy.

Contribution

The paper proposes a novel two-stage diffusion model with camera feature integration and a new low-light RAW dataset, advancing low-light image enhancement techniques.

Findings

Achieves state-of-the-art results on multiple datasets

Demonstrates strong generalization across different cameras

Ensures color consistency during diffusion process

Abstract

This paper presents a novel Two-Stage Diffusion Model (TS-Diff) for enhancing extremely low-light RAW images. In the pre-training stage, TS-Diff synthesizes noisy images by constructing multiple virtual cameras based on a noise space. Camera Feature Integration (CFI) modules are then designed to enable the model to learn generalizable features across diverse virtual cameras. During the aligning stage, CFIs are averaged to create a target-specific CFI$^T$, which is fine-tuned using a small amount of real RAW data to adapt to the noise characteristics of specific cameras. A structural reparameterization technique further simplifies CFI$^T$ for efficient deployment. To address color shifts during the diffusion process, a color corrector is introduced to ensure color consistency by dynamically adjusting global color distributions. Additionally, a novel dataset, QID, is constructed, featuring quantifiable illumination levels and a wide dynamic range, providing a comprehensive benchmark for training and evaluation under extreme low-light conditions. Experimental results demonstrate that TS-Diff achieves state-of-the-art performance on multiple datasets, including QID, SID, and ELD, excelling in denoising, generalization, and color consistency across various cameras and illumination levels. These findings highlight the robustness and versatility of TS-Diff, making it a practical solution for low-light imaging applications. Source codes and models are available at https://github.com/CircccleK/TS-Diff