Drawing in opencv

draw_opencv.py

import numpy as np
import cv2 as cv

# create a black image
img = np.zeros((512, 512, 3), np.uint8)

# Draw a diagonal blue line with thickness of 5 px
cv.line(img,(0,0),(512,512),(255,0,0),5)

# Draw a green rectangle with thickness of 3 px without fill
cv.rectangle(img,(384,0),(510,128),(0,255,0),3)

# Draw a red circle that has a fill
cv.circle(img,(447,63), 63, (0,0,255), -1)

# Draw an ellipse 
cv.ellipse(img,(256,256),(100,50),0,0,180,255,-1)

# Define points for a polygon
pts = np.array([[10,5],[20,30],[70,20],[50,10]], np.int32)

# Draw the polygon with points
cv.polylines(img,[pts],True,(0,255,255))

# Define the font style
font = cv.FONT_HERSHEY_SIMPLEX

# Draw the text
cv.putText(img,'OpenCV',(10,500), font, 4,(255,255,255),2,cv.LINE_AA)

# display image
cv.imshow("black image", img)

k = cv.waitKey(0)

if k == ord('x'):
    sys.exit("Exiting image")