If you have build OpenCV(>=4.7.0) by yourself, it provides a new api [`cv::dnn::NMSBoxesBatched`](https://docs.opencv.org/4.x/d6/d0f/group__dnn.html#ga977aae09fbf7c804e003cfea1d4e928c) .
It is a gread api about efficient in-class nms .
***Notice !!!***
You can build by `-DBATCHED_NMS` and try to use it .
``` shell
....
cmake .. -DBATCHED_NMS
....
```
If you have build OpenCV(>=4.7.0) by yourself, it provides a new api [`cv::dnn::NMSBoxesBatched`](https://docs.opencv.org/4.x/d6/d0f/group__dnn.html#ga977aae09fbf7c804e003cfea1d4e928c) .
It is a gread api about efficient in-class nms . It will be used by default!