Detecting rectangle with border in image

Python
1

I’m trying to find coordinates of rectangle border in the image https://i.stack.imgur.com/KKjfg.gif using opencv but I’m not able to achieve this instead I end up getting some random not present rectangles on image. Below is my code of the execution

import cv2
import numpy as np
import random as rng
image = cv2.imread('strawberry.png')
threshold = 100
grayscale= cv2.cvtColor(image,cv2.COLOR_BGR2GRAY)
canny_output = cv2.Canny(grayscale, threshold, threshold * 2)

ret, thresh= cv2.threshold(grayscale,200,255,cv2.THRESH_BINARY_INV)
contours, _ = cv2.findContours(canny_output,cv2.RETR_EXTERNAL,cv2.CHAIN_APPROX_NONE)
contours_poly = [None]*len(contours)
#boundRect = [None]*len(contours)
boundRect = list()
centers = [None]*len(contours)
radius = [None]*len(contours)
for i, c in enumerate(contours):
    contours_poly[i] = cv2.approxPolyDP(c, 3, True)
    if len(contours_poly[i]) == 4:
        boundRect.append(cv2.boundingRect(contours_poly[i]))
    #boundRect[i] = cv.boundingRect(contours_poly[i])
    #centers[i], radius[i] = cv.minEnclosingCircle(contours_poly[i])


drawing = np.zeros((canny_output.shape[0], canny_output.shape[1], 3), dtype=np.uint8)

print(len(boundRect))
#for i in range(len(contours)):
#    color = (rng.randint(0,256), rng.randint(0,256), rng.randint(0,256))
#    cv.drawContours(drawing, contours_poly, i, color)
#    cv.rectangle(drawing, (int(boundRect[i][0]), int(boundRect[i][1])), \
#      (int(boundRect[i][0]+boundRect[i][2]), int(boundRect[i][1]+boundRect[i][3])), color, 2)
#cv.circle(drawing, (int(centers[i][0]), int(centers[i][1])), int(radius[i]), color, 2)
for i in range(len(boundRect)):
    if boundRect[i][2]/boundRect[i][3] > 2:
        color = (rng.randint(0,256), rng.randint(0,256), rng.randint(0,256))
        cv2.rectangle(drawing, (int(boundRect[i][0]), int(boundRect[i][1])), \
            (int(boundRect[i][0]+boundRect[i][2]), int(boundRect[i][1]+boundRect[i][3])), color, 2)
        print(f'Rectangle X:{boundRect[i][0]}, Y:{boundRect[i][1]}, W:{boundRect[i][2]}, H:{boundRect[i][3]}')

I end up identifying random rectangles not the which I'm interested in like below
[detected rectangle output](https://i.stack.imgur.com/32QQx.png)

How can I detect rectangle coordinates present in image with white border? what am I doing wrong in my approach, any suggestions or guide on this will be very helpful thanks
2

related, with answer:

3

Tried it didn’t get expected output using python

4

can’t work with “it didn’t work”

every time you feel like saying “it didn’t work”, catch yourself, and instead say something that conveys information.

use python’s debugger on your code. report your findings.

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