CoLight-GS: Coupled Radiometric Supervision for Low-Light Gaussian Splatting

Low-light novel-view synthesis aims to reconstruct a well-exposed 3D scene from dark multi-view images. Exposure correction alters both the reconstruction tar- gets and the scales of image residuals, linking brightness recovery to how scene details are fitted. We present CoLight-GS, a Gaussian reconstruction framework that couples bright-domain structural supervision with dark-domain observation fitting through a fixed invertible tone map. The map lifts dark observations into bright targets, while its analytic inverse maps the same scene rendering back to the observed domain, jointly supervising a single Gaussian scene. A shared gain defines a coherent exposure convention across views with matching capture condi- tions, while source-histogram anchoring accommodates heterogeneous exposures. Derivative-based weighting coordinates the residual scales of the bright and ob- served domains. CoLight-GS requires no pretrained depth or restoration models and renders novel views directly with standard Gaussian splatting. On RealX3D and LOM, CoLight-GS outperforms five compared methods in mean PSNR, SSIM, and LPIPS, reaching 18.10 dB and 23.45 dB PSNR, respectively.