Draw a Line on an Image Using OpenCV

In this program, we will draw a simple line on an image using the OpenCV function line().

Original Image

Algorithm

Step 1: Import cv2.
Step 2: Read the image using imread().
Step 3: Get the dimensions of the image using the image.shape method.
Step 4: Define starting point of the line.
Step 5: Define the end point of the line.
Step 6: Define the thickness of the line.
Step 7: Draw the line using the cv2.line() function and pass Step 3 to Step 4 as parameters.

Example Code

import cv2

image = cv2.imread('testimage.jpg')
height, width, channels = image.shape
startpoint = (0, 0)
endpoint = (height, width)
thickness = 9
color = (255, 0, 0)
image = cv2.line(image, startpoint, endpoint, color, thickness)
cv2.imshow('Line', image)

Output

Explanation

As you can see, a blue line is drawn on the image.