1、pfld：车牌四角定位训练代码
reference：
PFLD: A Practical Facial Landmark Detector https://arxiv.org/pdf/1902.10859.pdf
Implementation of PFLD A Practical Facial Landmark Detector by pytorch. https://github.com/polarisZhao/PFLD-pytorch
2、crnn：车牌字符识别模型训练代码
reference：
An End-to-End Trainable Neural Network for Image-based Sequence Recognition and Its Application to Scene Text Recognition http://arxiv.org/abs/1507.05717
3、yolov5：车牌检测
reference：
https://github.com/ultralytics/YOLOv5
4、ncnn：
yolov5、pfld、crnn的ncnn c/c++推理DEMO