How to draw a circle on image in Opencv

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

Input image :

Code :

import cv2

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

cv2.circle(a, (500,500),30 ,(255,0,0),2)

cv2.imshow("img",a)

cv2.waitKey(0)

cv2.destroyAllWindows()

Let's try to understand how this code works

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
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
if you put the value of thickness -1 then you will get a filled circle
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
cv2.circle it takes 5 parameter
(image , center of other circle, radius of the circle , color , thickenss)
In our cases image is a center of circle is (500,500) ,radius is 30 (pixels) ,color is blue (255,0,0) , and thickness of the circle is 2.

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