cv2.circle()方法用于在任何图像上绘制圆。

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

参数：
image:它是要在其上绘制圆的图像。
center_coordinates：它是圆的中心坐标。坐标表示为两个值的元组，即(X坐标值，Y坐标值)。
radius:它是圆的半径。
color:它是要绘制的圆的边界线的颜色。对于BGR，我们通过一个元组。例如：(255，0，0)为蓝色。
thickness:它是圆边界线的粗细像素。厚度-1像素将以指定的颜色填充矩形形状。

返回值：它返回一个图像。

用于以下所有示例的图像：

示例1:

# 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)

输出：

示例2:
使用-1 px的厚度用红色填充矩形。

# 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)

输出：