中文说明：首先从视频中提取100张图片，用其中五十张图片根据平均值法获得背景图片，然后做差，二值化，提取目标。
English Description：
First, 100 images are extracted from the video, and 50 of them are used to get the background image according to the average method. Then, the target is extracted by subtraction and binarization.