Python OpenCV | cv2.line() method

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

Syntax:

cv2.line(image, start_point, end_point, color, thickness)

Parameters: image: It is the image on which line is to be drawn.

start_point: It is the starting coordinates of the line. The coordinates are represented as tuples of two values i.e. (X coordinate value, Y coordinate value).
end_point: It is the ending coordinates of the line. The coordinates are represented as tuples of two values i.e. (X coordinate value, Y coordinate value).
color: It is the color of the line to be drawn. For RGB, we pass a tuple. eg: (255, 0, 0) for blue color.
thickness: It is the thickness of the line in px.

Return Value: It returns an image.

Implementation:

The image used for examples n1 and 2 is as follows:

Example #1:

Python3

# Python program to explain cv2.line() 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'
  
# Start coordinate, here (0, 0)
# represents the top left corner of image
start_point = (0, 0)
  
# End coordinate, here (250, 250)
# represents the bottom right corner of image
end_point = (250, 250)
  
# Green color in BGR
color = (0, 255, 0)
  
# Line thickness of 9 px
thickness = 9
  
# Using cv2.line() method
# Draw a diagonal green line with thickness of 9 px
image = cv2.line(image, start_point, end_point, color, thickness)
  
# Displaying the image 
cv2.imshow(window_name, image) 

Output:

Example #2:

Python3

# Python program to explain cv2.line() method 
   
# importing cv2 
import cv2 
   
# path 
path = r'C:\Users\Rajnish\Desktop\geeksforgeeks\geeks.png'
   
# Reading an image in grayscale mode
image = cv2.imread(path, 0)
   
# Window name in which image is displayed
window_name = 'Image'
  
# Start coordinate, here (225, 0)
# represents the top right corner of image
start_point = (225, 0)
  
# End coordinate, here (0, 225)
# represents the bottom left corner of image
end_point = (0, 225)
  
# Black color in BGR
color = (0, 0, 0)
  
# Line thickness of 5 px
thickness = 5
  
# Using cv2.line() method
# Draw a diagonal black line with thickness of 5 px
image = cv2.line(image, start_point, end_point, color, thickness)
  
# Displaying the image 
cv2.imshow(window_name, image) 

Output:

Example 3: Drawing a line on black screen using numpy library:

Python3

import numpy as np
import cv2
# Creating a black screen image using numpy.zeros function
Img = np.zeros((512, 512, 3), dtype='uint8')
# Start coordinate, here (100, 100). It represents the top left corner of image
start_point = (100, 100)
# End coordinate, here (450, 450). It represents the bottom right corner of the image according to resolution
end_point = (450, 450)
# White color in BGR
color = (255, 250, 255)
# Line thickness of 9 px
thickness = 9
# Using cv2.line() method to draw a diagonal green line with thickness of 9 px
image = cv2.line(Img, start_point, end_point, color, thickness)
# Display the image
cv2.imshow('Drawing_Line', image)
cv2.waitKey(0)
cv2.destroyAllWindows()