[Opencv-python] cv2.scaleAdd(...) Image scaling and addition

1. Background

For detailed documentation, please refer to official information.
This blog is as simple and clear as possible. If there are any errors, please correct me.

The python and cv2 versions of this blog are as follows:

#python版本：
3.7.10|packaged by conda-forge|(default,Feb 19 2021,15:37:01)[MSCv.1916 64 bit(AMD64)]
#opencv-python版本：
opencv-python:4.5.1.48

opencv provides an api for image scaling and addition:

cv2.scaleAdd