背景提取，迭代法(Surendra算法）；即采用帧差的方法，一帧图像减去前一帧图像，即可以对比得到图像中变化（移动）的区域，扣除移动的区域，即得到不动的背景。采用多帧图像迭代的方法，得到更加准确的背景。-Background extraction, iterative method (Surendra algorithm)　fr a me difference method is used, an image by subtracting the previous fr a me, which can receive the image contrast change (movement) of the area, less the area of ​ ​ movement, that is obtained immovable background. Multi-fr a me image iteration method, to be more accurate background.