OpenCV running otsu thresh on video gives weird window

Question

I am trying to run this opencv code to run otsu tresh on my image and get mask

import cv2
import numpy as np


video = cv2.VideoCapture('video.mp4')
 
 
# loop runs if capturing has been initialized
while True:
 
    # reads frames from a camera
    ret, frame = video.read()
    
    original = frame.copy()
    mask = np.zeros(frame.shape, dtype=np.uint8)
    gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)

    thresh = cv2.threshold(gray, 0, 255, cv2.THRESH_BINARY_INV + cv2.THRESH_OTSU)[1]
    kernel = cv2.getStructuringElement(cv2.MORPH_RECT, (5,5))
    opening = cv2.morphologyEx(thresh, cv2.MORPH_OPEN, kernel, iterations=3)

    cnts = cv2.findContours(opening, cv2.RETR_EXTERNAL, cv2.CHAIN_APPROX_SIMPLE)
    cnts = cnts[0] if len(cnts) == 2 else cnts[1]
    cnts = sorted(cnts, key=cv2.contourArea, reverse=True)
    for c in cnts:
        cv2.drawContours(mask, [c], -1, (255,255,255), -1)
        break

    close = cv2.morphologyEx(mask, cv2.MORPH_CLOSE, kernel, iterations=4)
    close = cv2.cvtColor(close, cv2.COLOR_BGR2GRAY)
    result = cv2.bitwise_and(original, original, mask=close)
    result[close==0] = (255,255,255)


    cv2.imshow('result', result)
video.release()
 
# De-allocate any associated memory usage
cv2.destroyAllWindows()

This is giving me a weird frame window like below

Nothing happens for about 20 seconds until it warns me the program will crash. The only output I get is Killed

This is how the image looks like:

What is causing this and how do I fix it?

Answer 1

You are missing cv2.waitKey(). Put this after cv2.imshow()

    cv2.imshow('result', result)
    cv2.waitKey(0)
video.release()