import cv2

def diffImg(t0, t1, t2):

return cv2.bitwise_and(d1, d2)

cam = cv2.VideoCapture(0)

winName = "Movement Indicator"

cv2.namedWindow(winName, cv2.CV_WINDOW_AUTOSIZE)

# Read three images first:

t_minus = cv2.cvtColor(cam.read()[1], cv2.COLOR_RGB2GRAY)

t = cv2.cvtColor(cam.read()[1], cv2.COLOR_RGB2GRAY)

t_plus = cv2.cvtColor(cam.read()[1], cv2.COLOR_RGB2GRAY)

while True:

cv2.imshow( winName, diffImg(t_minus, t, t_plus) )

# Read next image

t_minus = t

t = t_plus

t_plus = cv2.cvtColor(cam.read()[1], cv2.COLOR_RGB2GRAY)

key = cv2.waitKey(10)

if key == 27:

cv2.destroyWindow(winName)

break

print "Goodbye"