Add more detailed description of bilateral filter

skimage/filter/denoise.py

@@ -246,6 +246,17 @@ def denoise_bilateral(image, win_size=5, sigma_color=1, sigma_range=1, bins=1e4,
                       mode='constant', cval=0):
     """Denoise image using bilateral filter.
 
+    This is an edge-preserving and noise reducing denoising filter. It averages
+    pixel based on their spatial closeness and radiometric similarity.
+
+    Spatial closeness is measured by the gaussian function of the euclidian
+    distance between two pixels and a certain standard deviation
+    (`sigma_range`).
+
+    Radiometric similarity is measured by the gaussian function of the euclidian
+    distance between two color values and a certain standard deviation
+    (`sigma_color`).
+
     Parameters
     ----------
     image : ndarray