RaspberryPi＋WEBカメラで入退室時にゆかり様にお疲れ様ですと 改良版

動体検知をOpenCVで実装するしかないな（

# -*- coding: utf-8 -*-
import cv2
import numpy as np
import time
import commands

DURATION = 1.0

#取得する画像の解像度
WIDTH = 320
HEIGHT = 240

camera = cv2.VideoCapture(0)
camera.set(3, WIDTH)
camera.set(4, HEIGHT)
camera.set(5, 15)# FPS

retval, frame = camera.read()

hist_32 = np.zeros((HEIGHT, WIDTH), np.float32)
frame_pre = frame

while(camera.isOpened()):
    retval, frame = camera.read()

    # 直前フレームとの差分を抽出
    diff = cv2.absdiff(frame, frame_pre)
    # グレースケール変換
    diff = cv2.cvtColor(diff, cv2.COLOR_BGR2GRAY)
    #　差分画像２値化 第二引数が抽出する動きの領域のしきい値
    retval, diff = cv2.threshold(diff, 30, 255, cv2.THRESH_BINARY)

    times_s = time.clock()
    # 履歴画像の作成
    cv2.updateMotionHistory(diff, hist_32, times_s, DURATION)
    # 履歴画像から動きの方向を計算
    hist_8, direction = cv2.calcMotionGradient(hist_32, 0.25, 0.05, apertureSize=5)
    # 履歴画像と方向から全体の動き方向を計算
    angle = cv2.calcGlobalOrientation(direction, hist_8, hist_32, times_s, DURATION)
    if 170 < angle < 190:
        print "<-----"
        cv2.imwrite("tmp.jpg",frame)
        print commands.getoutput("img2sixel tmp.jpg")
    if angle > 340:
        print "----->"
        cv2.imwrite("tmp.jpg",frame)
        print commands.getoutput("img2sixel tmp.jpg")