How to draw line on image in OpenCv Python

Video Explanation: 

As we all know a image in nothing a 2d graph in which several pixels are there arranging rows and colum

Note : I am assuming that you image is in the same folder where your python code is saving if you then you need to give proper directory

Image taken as input : 

Code:

import cv2

a = cv2.imread('1.jpg')

start= (0,0)

end = (500,500)

cv2.line(a,start,end,(255,0,0),2)

cv2.imshow("line",a)

cv2.waitKey(0)

cv2.destroyAllWindows()

You can also write this code like this

import cv2

a = cv2.imread('1.jpg')

cv2.line(a,(0,0),(500,500),(255,0,0),2)

cv2.imshow("line",a)

cv2.waitKey(0)

cv2.destroyAllWindows()

Let's try to understand how this code work

• Fist we have import cv2 so that we can use opencv in our code
• After we are reading our image by using command cv2.imread and store this image into a variable called a
• Now we need to define a starting point and ending point of a line .Remember that image is nothing just a 2D graph
• Now let's try to understand cv2.line working
   cv2.line(image_name, starting_point_of _line ,ending_point_of_line , color_of_the_line ,thickness_of_the_line)
  Note: Opencv by default sotre image in BGR format so (255,0,0) means highest value of blue color scale , lowest value of green color scale ,lowest value of red color scale .
  Recommend try to play with these value
  After that we define thickness that is 2 here 2 means 2 pixels thickness of the line
• cv2.imshow("line",a) 
  here "line" is the window name in which we are going to show our image and a is the name of the image that we want to show
• cv2.waitKey(0)
• cv2.destroyAllWindows()
  the purpose of cv2.waitKey(0) that after output it will stay on the screen until any keypad is pressed and cv2.destroyAllWindows() make sure to close out window properly