Python OpenCV | cv2.line() method
Last Updated :
04 Jul, 2024
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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:
# 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:
# 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:
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
