说明：  添加噪声与平滑降噪,平滑降噪可采用定制的模板做滤波运算（就是卷积运算）来获得中心像素的新值，也可以对指定大小的邻域进行某些运算作为中心像素的新值.
(Add noise and smooth noise reduction, smoothing noise reduction can be customized templates so filtering operation (that is convolution operation) to receive the new pixel value, can also specify the size of neighborhood to perform certain operations as the central pixel of the new value.)