import cv2
video=cv2.VideoCapture(0)
first_frame=None

while True:
    check,frame=video.read()
    gray=cv2.cvtColor(frame,cv2.COLOR_BGR2GRAY)
    gray=cv2.GaussianBlur(gray,(21,21),0)

    if first_frame is None:
        first_frame=gray
        continue

    delta_frame=cv2.absdiff(first_frame,gray)
    thresh_frame=cv2.threshold(delta_frame,30,255,cv2.THRESH_BINARY)[1]
    thresh_frame=cv2.dilate(thresh_frame,None,iterations=2)


    (_,cnts,_)=cv2.findContours(thresh_frame.copy(),cv2.RETR_EXTERNAL,cv2.CHAIN_APPROX_SIMPLE)

    for contour in cnts:
        if cv2.contourArea(contour) < 1000:
            continue

        (x,y,w,h)=cv2.boundingRect(contour)
        cv2.rectangle(frame,(x,y),(x+w,y+h),(255,255,0),4)


    cv2.imshow("thresh",thresh_frame)
    cv2.imshow("delta frame",delta_frame)
    cv2.imshow("gray",gray)
    cv2.imshow("frame",frame)
    key=cv2.waitKey(1)
    if key ==ord("q"):
        break

video.release()
cv2.destroyAllWindows()