Crop Circular image simple app using opencv Python

 Crop Circular image simple app using opencv Python

In this blog we are going to learn how to crop an image in circle shape using mouse in opencv python

After creating the Circle of desired shape Press C to crop the image

import cv2

import numpy as np

img = cv2.imread('cat.jpg')

img_dup = np.copy(img)

mouse_pressed = False

# defining starting and ending point of circle(crop image region)

starting_x = starting_y = ending_x = ending_y = -1

def mousebutton(event, x, y, flags, param):

    global img_dup, starting_x, starting_y, ending_x, ending_y, mouse_pressed

    # if left mouse button is pressed then takes the cursor position at starting_x and starting_y

    if event == cv2.EVENT_LBUTTONDOWN:

        mouse_pressed = True

        starting_x, starting_y = x, y

        img_dup = np.copy(img)

    elif event == cv2.EVENT_MOUSEMOVE:

        if mouse_pressed:

            img_dup = np.copy(img)

            radius = np.sqrt((x - starting_x)**2 + (y - starting_y)**2)

            cv2.circle(img_dup, (starting_x, starting_y), int(radius), (0, 255, 0), 1)

            

    # final position of circle if left mouse button is up then takes the cursor position at ending_x and ending_y

    elif event == cv2.EVENT_LBUTTONUP:

        mouse_pressed = False

        ending_x, ending_y = x, y

cv2.namedWindow('image')

cv2.setMouseCallback('image', mousebutton)

while True:

    cv2.imshow('image', img_dup)

    k = cv2.waitKey(1)

    if k == ord('c'):

        # remove these condition and try to play weird output will give you idea why its done

        if starting_x > ending_x:

            starting_x, ending_x = ending_x, starting_x

        if ending_y - starting_y > 1 and ending_x - starting_x > 0:

            radius = np.sqrt((ending_x - starting_x)**2 + (ending_y - starting_y)**2)

            mask = np.zeros_like(img)  # create a mask with the same size as the image

            cv2.circle(mask, (starting_x, starting_y), int(radius), (255, 255, 255), -1)  # draw a white circle on the mask

            cropped_img = cv2.bitwise_and(img, mask)  # apply the mask to the image

            img_dup = np.copy(cropped_img)

    elif k == 27:

        break

cv2.destroyAllWindows()

Other Blog :
Crop Rectangle Image simple app using openCV Python