程序原理为采用avicap调用摄像头，然后通过设置监控对比图像，当摄像头中的图像与监控对比图像不一致时，即发出警报并可以自动发送当前监控图像到指定邮箱中-The program theory avicap call camera, then set monitor contrast image, when the image in the camera and monitor contrast image is inconsistent, that is an alarm and automat