#!/usr/bin/env python
import sys
import cv2
import numpy as np

file_or_dev = sys.argv[1] if len(sys.argv) > 1 else 0

def nothing(*arg):
    pass

cv2.namedWindow('dvs')
cv2.createTrackbar('T', 'dvs', 10, 100, nothing)

cap = cv2.VideoCapture(file_or_dev)
_, img = cap.read()
prev = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY) >> 1
while 1:
    _, img = cap.read()
    gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY) >> 1
    diff = 128 + prev - gray
    prev = gray
    cv2.imshow('diff', diff.astype('uint8'))
    # cv2.imwrite('diff.%05i.png'%inc, diff.astype('uint8'))
    T = cv2.getTrackbarPos('T', 'dvs')
    img[...,0] = 0 # img is BGR
    img[...,1] = np.where(diff > (128 + T), diff, 0)
    img[...,2] = np.where(diff < (128 - T), 255 - diff, 0)
    cv2.imshow('dvs', img)
    if cv2.waitKey(1) == 27:
        break