均值滤波：把每个像素周围的8个像素来做均值操作，可以平滑图像，速度快，算法简单，但是无法去掉噪声，只能微弱的减弱它。-The mean filtering: 8 pixels around each pixel do mean, you can smooth image, fast and simple algorithm, but can not get rid of the noise, only faint weakened it.