# 1, Line segment drawing

cv2.line(dst,(100,100),(400,400),(0,0,255),2,cv2.LINE_AA)
Parameter 1: target picture data
Parameter 2: the starting position of the current line segment (that is, two points determine a straight line)
Parameter 3: the ending position of the current line segment (that is, two points determine a straight line)
Parameter 4: current line segment color (B,G,R)
Parameter 5: width of current line segment
Parameter 6: set the type of current line segment

import cv2
import numpy as np
newImageInfo = (500,500,3)#The size of the target picture
dst = np.zeros(newImageInfo,np.uint8)#Create a target picture

#Draw line segments
cv2.line(dst,(100,100),(400,400),(0,0,255))
cv2.line(dst,(100,200),(400,200),(0,255,0),5)
cv2.line(dst,(100,300),(400,300),(255,0,0),20,cv2.LINE_AA)
#Of course, you can also draw triangles, rectangles and other shapes, just a few more line segments
cv2.imshow('dst',dst)
cv2.waitKey(0)

The renderings are as follows:

# 2, Rectangle, circle and freeform polygon drawing

cv2.rectangle(dst,(50,100),(200,300),(255,0,0),-1)
Parameter 1: current target image
Parameter 2: starting point of the upper left corner of the rectangle
Parameter 3: lower right corner of rectangle
Parameter 4: rectangle color
Parameter 5: fill- 1. Filling is required; Other positive values are the width of the rectangular edge

cv2.circle(dst,(250,250),(50),(0,255,0),2)
Parameter 1: current target image
Parameter 2: position of circle center
Parameter 3: radius of circle
Parameter 4: line color of drawing circle
Parameter 5: fill; If - 1 indicates filling; For other positive values, surface line width

cv2.ellipse(dst,(256,256),(150,100),0,0,180,(255,255,0),-1)
Parameter 1: current target image
Parameter 2: Oval circle
Parameter 3: the length of the axis. Because the ellipse has two axes, it has two values
Parameter 4: deflection angle
Parameter 5: starting angle of arc
Parameter 6: end angle of arc
Parameter 7: line color
Parameter 8: fill; If - 1 indicates filling; For other positive values, surface line width

import cv2
import numpy as np
newImageInfo = (500,500,3)
dst = np.zeros(newImageInfo,np.uint8)

#draw rectangle
cv2.rectangle(dst,(50,100),(200,300),(255,0,0),-1)

#Draw circle
cv2.circle(dst,(250,250),(50),(0,255,0),2)

#Oval, sector and arc
cv2.ellipse(dst,(256,256),(150,100),0,0,180,(255,255,0),-1)

#Freeform polygon
points = np.array([[150,50],[140,140],[200,170],[250,250],[150,50]],np.int32)
#print(points.shape)
points = points.reshape((-1,1,2))
#print(points.shape)
cv2.polylines(dst,[points],True,(0,255,255))

cv2.imshow('dst',dst)
cv2.waitKey(0)

The renderings are as follows:

# 3, Text and picture drawing

cv2.rectangle(img,(20,20),(250,250),(0,255,0),3)
Parameter 1: original image
Parameter 2: starting position of the box
Parameter 3: end position of box
Parameter 4: box color
Parameter 5: fill; If - 1 indicates filling; For other positive values, surface line width

cv2.putText(img,'this is a cat',(45,45),font,1,(0,0,255),2,cv2.LINE_AA)
Parameter 1: target image
Parameter 2: text content
Parameter 3: written coordinates
Parameter 4: font type
Parameter 5: font size
Parameter 6: font color
Parameter 7: font weight
Parameter 8: font line type

import cv2
import numpy as np
font = cv2.FONT_HERSHEY_SIMPLEX#Select font
cv2.rectangle(img,(20,20),(250,250),(0,255,0),3)#Draw a small box
cv2.putText(img,'this is a cat',(45,45),font,1,(0,0,255),2,cv2.LINE_AA)
cv2.imshow('src',img)
cv2.waitKey(0)

The renderings are as follows:

cv2.resize(img,(width,height))
Parameter 1: selected photos
Parameter 2: set the width and height of the photo

import cv2