[Opencv-python] cv2.line(...) draws a straight line

1. Background

Draw a straight line segment: Draw by connecting two points.

The interface of cv2 drawing straight line segment:

cv2.line(img,pt1,pt2,color[,thickness[,lineType[,shift]]])-> img

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

python:3.7.9 (default, Aug 31 2020, 17:10:11) [MSC v.1916 64