双边滤波器，一种可以保边去噪的滤波器，滤波器是由两个函数构成。一个函数是由几何空间距离决定滤波器系数。另一个由像素差值决定滤波器系数-Bilateral filter, a way to protect the edge denoising filter, the filter is constituted by two functions. A function is decided by the geometric spatial distance filter coefficients.