Enhancing small target traffic sign detection with ML_SAP in YOLOv5s

Detecting small traffic signs poses significant challenges due to the complex nature and dynamic conditions of real-world traffic scenarios. In response to these challenges, we propose an improved YOLOv5s target detection model incorporating the multilevel squeeze feature perception (ML_SAP) mechanism, aiming to increase the accuracy of small traffic sign detection. First, an additional detection layer is incorporated to enhance the model's capacity for detecting small-scale traffic signs. This improvement is accompanied by the adoption of a WIoU loss function, which evaluate the quality of anchor boxes. Moreover, the ML_SAP mechanism is designed to promotes the fusion and extraction of features at different levels. This mechanism effectively increases the network model's proficiency in identifying small targets under varying environmental conditions. To verify the effectiveness of the improved method, we conducted extensive experiments on two public transportation sign datasets. Notably, on the challenging samples in the CCTSDB-2021 dataset, the improved model achieves a detection recall of 77.1%, which is 5.4% higher than that of YOLOv5s, and a mean average precision (mAP) of 82.7%, which is 3.9% higher than that of the base model. Furthermore, the model achieves a detection recall of 91.3% on the TT100K dataset, which is 3.7% higher than the performance of YOLOv5s, and a mean precision (mAP) of 91.5%, which is 4.6% higher than that of the base model.