An Improved Object Detection Method for Underwater Sonar Image Based on PP-YOLOv2

Table 1

Eight object categories and their numbers of images and objects in forward sonar data.

(a) Object information in training data

Object category	Number of objects	Number of images
Ball	1943	1941
Circle cage	386	383
Cube	1752	1749
Cylinder	402	401
Human body	684	683
Metal bucket	403	402
Square cage	655	655
Tyre	852	850
Total	7077	4000

(b) Object information in test data

Object category	Number of objects	Number of images
Ball	595	595
Circle cage	86	86
Cube	424	423
Cylinder	39	39
Human body	379	379
Metal bucket	44	43
Square cage	169	169
Tyre	108	108
Total	1844	1000