One stage multi-scale efficient network for underwater target detection.

Due to the complexity of the underwater environment, existing methods for underwater target detection present low precision on small or dense targets. To address these issues, a novel method is proposed for underwater target detection based on YOLOv5s (You Only Look Once version 5 small), which aims to improve the precision and robustness. In this study, an efficient feature extraction network is introduced to extract significant features, and a novel attention mechanism with deformable convolution is designed to improve the feature representation. Subsequently, an adaptive spatial fusion operation is introduced at the neck of YOLOv5s to facilitate feature fusion from various layers. By integrating low-level features with high-level features, the adaptive fusion feature pyramid network effectively integrates global semantic information and decreases the semantic gap between features from various layers, contributing to the high detection precision. Comprehensive experiments demonstrate that the proposed method achieves an mAP50 of 86.97% on the Underwater Robot Professional Contest of China 2020 dataset, 3.07% higher than YOLOv5s. Furthermore, the proposed method achieves a detection precision of 76.0% on the PASCAL VOC2007 dataset, surpassing several outstanding methods.