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Python OpenCV | cv2.line() method

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  • Last Updated : 22 Nov, 2022
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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()

Output:

Black Screen created using numpy and drawing line using cv2.line() function


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