Python OpenCV | cv2.circle() method

OpenCV-Python is a library of Python bindings designed to solve computer vision problems. cv2.circle() method is used to draw a circle on any image. The syntax of cv2.circle() method is:

Syntax:

cv2.circle(image, center_coordinates, radius, color, thickness)

Parameters:

image: It is the image on which the circle is to be drawn.
center_coordinates: It is the center coordinates of the circle. The coordinates are represented as tuples of two values i.e. (X coordinate value, Y coordinate value).
radius: It is the radius of the circle.
color: It is the color of the borderline of a circle to be drawn. For BGR, we pass a tuple. eg: (255, 0, 0) for blue color.
thickness: It is the thickness of the circle border line in px. Thickness of -1 px will fill the circle shape by the specified color.

Return Value: It returns an image.

The steps to create a circle on an image are:

Read the image using imread() function.
Pass this image to the cv2.circle() method along with other parameters such as center_coordinates, radius, color and thickness.
Display the image using cv2.imshow() method.

Implementation:

Image used for all the below examples:

Example #1:

Python3

# Python program to explain cv2.circle() method 
    
# importing cv2 
import cv2 
    
# path 
path = r'C:\Users\Rajnish\Desktop\geeksforgeeks\geeks.png'
    
# Reading an image in default mode
image = cv2.imread(path)
    
# Window name in which image is displayed
window_name = 'Image'
   
# Center coordinates
center_coordinates = (120, 50)
  
# Radius of circle
radius = 20
   
# Blue color in BGR
color = (255, 0, 0)
   
# Line thickness of 2 px
thickness = 2
   
# Using cv2.circle() method
# Draw a circle with blue line borders of thickness of 2 px
image = cv2.circle(image, center_coordinates, radius, color, thickness)
   
# Displaying the image 
cv2.imshow(window_name, image) 

Output:

Example #2: Using thickness of -1 px to fill the circle with red color.

Python3

# Python program to explain cv2.circle() method 
    
# importing cv2 
import cv2 
    
# path 
path = r'C:\Users\Rajnish\Desktop\geeksforgeeks\geeks.png'
    
# Reading an image in default mode
image = cv2.imread(path)
    
# Window name in which image is displayed
window_name = 'Image'
   
# Center coordinates
center_coordinates = (120, 100)
  
# Radius of circle
radius = 30
   
# Red color in BGR
color = (0, 0, 255)
   
# Line thickness of -1 px
thickness = -1
   
# Using cv2.circle() method
# Draw a circle of red color of thickness -1 px
image = cv2.circle(image, center_coordinates, radius, color, thickness)
   
# Displaying the image 
cv2.imshow(window_name, image) 
  

Output:

Example # 3: To display a circle on a black screen created using NumPy library.

Python3

import cv2
import numpy as np
     
  
# Reading an image in default mode
Img = np.zeros((512, 512, 3), np.uint8)
     
# Window name in which image is displayed
window_name = 'Image'
    
# Center coordinates
center_coordinates = (220, 150)
   
# Radius of circle
radius = 100
    
# Red color in BGR
color = (255, 133, 233)
    
# Line thickness of -1 px
thickness = -1
    
# Using cv2.circle() method
# Draw a circle of red color of thickness -1 px
image = cv2.circle(Img, center_coordinates, radius, color, thickness)
    
# Displaying the image
cv2.imshow(window_name, image)
cv2.waitKey(0)
cv2.destroyAllWindows()