nms refer to : https://github.com/Nuzhny007/Non-Maximum-Suppression
code explain: http://fatalfeel.blogspot.com/2022/04/hog-pca-svm-slider-nms-in-c.html
Guide by Dr. Chen
opencv dlib cpp
http://fatalfeel.blogspot.com/2013/12/opencv-and-dlib-training.html
cpu is i7-3770k of year 2012, detect 512x512 image in 21 fps