import cv2

import numpy as np

camera=cv2.VideoCapture(0)

firstframe=None

while True:

    ret,frame = camera.read()

    if not ret:

        break

    gray=cv2.cvtColor(frame,cv2.COLOR_BGR2GRAY)

    gray=cv2.GaussianBlur(gray,(21,21),0)

    if firstframe is None:

        firstframe=gray

        continue  

    frameDelta = cv2.absdiff(firstframe,gray)

    thresh = cv2.threshold(frameDelta, 25, 255, cv2.THRESH_BINARY)[1]

    thresh = cv2.dilate(thresh, None, iterations=2)

    # cnts= cv2.findContours(thresh.copy(),cv2.RETR_EXTERNAL,cv2.CHAIN_APPROX_SIMPLE)  

    x,y,w,h=cv2.boundingRect(thresh)

    frame=cv2.rectangle(frame,(x,y),(x+w,y+h),(0,0,255),2)

    cv2.imshow("frame", frame)

    cv2.imshow("Thresh", thresh)

    cv2.imshow("frame2", frameDelta)

    key = cv2.waitKey(1)&0xFF  

    if key == ord("q"):

        break  

camera.release()

cv2.destroyAllWindows()