Enhancing nighttime vehicle detection with day-to-night style transfer and labeling-free augmentation

Deep learning-based object detection models perform well under daytime conditions but face significant challenges at night, primarily because they are predominantly trained on daytime images. Additionally, training with nighttime images presents another challenge: Even human annotators struggle to accurately label objects in low-light conditions. This issue is particularly pronounced in transportation applications, such as detecting vehicles and other objects of interest on rural roads at night, where street lighting is often absent, and headlights may introduce undesirable glare. In this study, we addressed these challenges by introducing a novel framework for labeling-free data augmentation, leveraging synthetic data generated by the Car Learning to Act (CARLA) simulator for day-to-night image style transfer. Specifically, the framework incorporated the efficient attention Generative Adversarial Network for realistic day-to-night style transfer and used CARLA-generated synthetic nighttime images to help the model learn the vehicle headlight effect. To evaluate the efficacy of the proposed framework, we fine-tuned the state-of-the-art object detection model with an augmented dataset curated for rural nighttime environments, achieving significant improvements in nighttime vehicle detection. This novel approach was simple yet effective, offering a scalable solution to enhance deep learning-based detection systems in low-visibility environments and extended the applicability of object detection models to broader real-world contexts.