https://blog.csdn.net/qq_35392791/article/details/123813363
https://www.zhihu.com/tardis/bd/art/94162374?source_id=1001
https://blog.csdn.net/qq_45738177/article/details/124518712
sudo apt-get install php7.3-gd
纯js识别字母与图像
https://github.com/mateogianolio/ocr/tree/master
++++++++++++++++
python + opencv
https://blog.csdn.net/m0_56531210/article/details/123512942
没有X
https://blog.csdn.net/a497785609/article/details/131398010
完整例子
https://blog.csdn.net/wFitting/article/details/124039827
一个开源库
https://github.com/PaddlePaddle/PaddleOCR/blob/release/2.6/README_ch.md