从视频图像序列中，每隔一定间隔提取出一幅图像，并采用中值法提取背景图像-get a background from a video with mean method

程序实现一个自适应阈值的算法，用以在不规则光照下从背景中提取出前景图像。-Procedures to achieve an adaptive threshold algorithm to extract the foreground from the background image in the irregular light.