Simple pythonscript to detect motion using a webcam

motiondetect.py

#!/bin/python
import numpy as np
import cv2

def diffImg(i0,i1,i2):
    d1 = cv2.absdiff(i2, i1)
    d2 = cv2.absdiff(i1, i0)
    return cv2.bitwise_and(d1, d2)

cap = cv2.VideoCapture(0)

def getImg():
    return cv2.cvtColor(cap.read()[1], cv2.COLOR_BGR2GRAY)


t1 = getImg()
t2 = getImg()
t3 = getImg()

motionlevel = 0

while True:
    diff = diffImg(t1, t2, t3)

    ret, diff = cv2.threshold(diff, 20, 255, cv2.THRESH_BINARY)

    nz = cv2.countNonZero(diff) * 1.

    height, width = diff.shape

    if motionlevel < 40:
        motionlevel+=nz/(height * width) * 2000
    if motionlevel > 0:
        motionlevel-=1;

    if motionlevel > 3:
        print "Motion:", motionlevel

    cv2.imshow('frame', diff)

    # count pixels

    t1 = t2
    t2 = t3
    t3 = getImg()
   
    if cv2.waitKey(1) & 0xFF == ord('q'):
        break;

cap.release()
cv2.destroyAllWindows()