[year] 2006
[source] ECCV
A bilateral filter is an edge-preserving and noise reducing smoothing filter. The intensity value at each pixel in an image is replaced by a weighted average of intensity values from nearby pixels. This weight is based on a Gaussian distribution. Crucially the weights depend not only on Euclidean distance but also on the radiometric differences (differences in the range, e.g. color intensity). This preserves sharp edges by systematically looping through each pixel and according weights to the adjacent pixels accordingly. 【from wiki】
双边滤波中使用了两个高斯函数，其中一个与距离有关，可预计算，另一个与两个强度差有关，则不能，因此>10min
本文中，通过增加一个维度，把两个函数合并成了一个,可预计算，因而用效。
[code] http://people.csail.mit.edu/sparis/bf/#code
sig notes作的很漂亮，很清楚，一图胜千言