Unsure what the problem is with canny edge detection issues

Python
1

Hi. I am new to opencv, and after reading some documentation have combined it with mss. I am trying to implement edge detection to detect objects in a game. However, I am facing an issue where the objects continuously flicker randomly. I am unsure what to do to fix it. Can someone point me in the right direction? Many thanks. Here is an attached video: (lots of flashing) Imgur: The magic of the Internet

You can see that most of the time the objects are caught correctly, yet sometimes the whole screen becomes flashbanged etc.

import time
import pygetwindow as gw

import cv2
import numpy as np

import mss
width = 1920 
height = 1080
offset = 200

x1 = width // 2 - offset
y1 = height // 2 - offset
        
x2 = width // 2 + offset
y2 = height // 2 + offset

with mss.mss() as sct:
    # Part of the screen to capture
    
    monitor = {"top": 0, "left": 0, "width": 1920, "height": 1080}
    
    while "Screen capturing":
        last_time = time.time()
        

        # region in middle of screen to cut out
        
        img = np.array(sct.grab(monitor))
        crop = img[y1:y2, x1:x2]
        img[y1:y2, x1:x2] = [0,0,0,255]
        gray = cv2.cvtColor(img, cv2.COLOR_BGRA2GRAY)
        
        edges = cv2.Canny(gray,100,200)
        kernel = np.ones((3,3), np.uint8)

        closing = cv2.morphologyEx(edges, cv2.MORPH_CLOSE, kernel)
        contours, _ = cv2.findContours(closing, cv2.RETR_EXTERNAL, cv2.CHAIN_APPROX_SIMPLE)

        filled_img = np.zeros_like(closing)

        cv2.drawContours(filled_img, contours, -1, (255), thickness=cv2.FILLED)

        cv2.imshow("Filled Ships", filled_img)

        print(f"fps: {1 / (time.time() - last_time)}")
        # Press "q" to quit
        if cv2.waitKey(1) & 0xFF == ord("q"):
            cv2.destroyAllWindows()
            break
2

are you telling me that you are capturing the window that you show the capture in?

what happens when you point a video camera at a TV screen that shows the video camera feed?

3

i know. that screen recording is my second display so there is no droste effect prevalent