HMNNet: research on exposure-based nighttime semantic segmentation

In recent years, various segmentation models have been developed successively. However, due to the limited availability of nighttime datasets and the complexity of nighttime scenes, there remains a scarcity of high-performance nighttime semantic segmentation models. Analysis of nighttime scenes has revealed that the primary challenges encountered are overexposure and underexposure. In view of this, our proposed Histogram Multi-scale Retinex with Color Restoration and No-Exposure Semantic Segmentation Network model is based on semantic segmentation of nighttime scenes and consists of three modules and a multi-head decoder. The three modules—Histogram, Multi-Scale Retinex with Color Restoration (MSRCR), and No Exposure (N-EX)—aim to enhance the robustness of image segmentation under different lighting conditions. The Histogram module prevents over-fitting to well-lit images, and the MSRCR module enhances images with insufficient lighting, improving object recognition and facilitating segmentation. The N-EX module uses a dark channel prior method to remove excess light covering the surface of an object. Extensive experiments show that the three modules are suitable for different network models and can be inserted and used at will. They significantly improve the model’s segmentation ability for nighttime images while having good generalization ability. When added to the multi-head decoder network, mean intersection over union increases by 6.2% on the nighttime dataset Rebecca and 1.5% on the daytime dataset CamVid.