Being effective and efficient is essential to an object detector for practical use. To meet these two concerns, we comprehensively evaluate a collection of existing refinements to improve the performance of PP-YOLO while almost keep the infer time unchanged. This paper will analyze a collection of refinements and empirically evaluate their impact on the final model performance through incremental ablation study. Things we tried that didn't work will also be discussed. By combining multiple effective refinements, we boost PP-YOLO's performance from 45.9% mAP to 49.5% mAP on COCO2017 test-dev. Since a significant margin of performance has been made, we present PP-YOLOv2. In terms of speed, PP-YOLOv2 runs in 68.9FPS at 640x640 input size. Paddle inference engine with TensorRT, FP16-precision, and batch size = 1 further improves PP-YOLOv2's infer speed, which achieves 106.5 FPS. Such a performance surpasses existing object detectors with roughly the same amount of parameters (i.e., YOLOv4-CSP, YOLOv5l). Besides, PP-YOLOv2 with ResNet101 achieves 50.3% mAP on COCO2017 test-dev. Source code is at https://github.com/PaddlePaddle/PaddleDetection.

通过综合评估现有的改进 refinement 的集合以改善 PP-YOLO 的性能，并为实现几乎不改变推理时间的效果，逐步进行消融研究以评估它们对最终模型性能的影响，通过结合多种有效的精炼手段，将 PP-YOLO 的性能从 45.9% mAP 提升到 49.5% mAP，而 PP-YOLOv2 的速度也达到了 106.5 FPS 的推理速度，由此超越了具有相同参数（即 YOLOv4-CSP，YOLOv5l）的现有目标检测器。

PP-YOLOv2: 实用物体检测器