转载至模型部署之 onNX ONNXRuntime
cv2.dnn.readNet源码 scrfd-opencv（使用opencv加载onnx模型进行推理）
Note：
scrfd(2021.5)能在opecv-python 4.5.5.64下运行，不能在opecv-python 4.52.0.34运行，即opecv-python 4.52.0.34的cv2.dnn.readNet()读取会报错：
OPENCV 4.0.0-beta onnx_importer.cpp:56: error: (-210:Unsupported format or combination of formats) Failed to parse onnx model in function 'ONNXimporter
参考 https://github.com/opencv/opencv/issues/12869
