Merge pull request #2764 from kif/spotty

tutorial on spotty data

Author: kif

doc/source/usage/tutorial/Spotty.ipynb

@@ -34,6 +34,7 @@ a good Python fluency and to a certain extent, of the pyFAI library.
    Performances-2D
    symmetrize
    multi-geometry
+   Spotty
    Goniometer/index
    Inpainting/Inpainting
    ThickDetector/index

doc/source/usage/tutorial/index.rst

@@ -715,7 +715,13 @@ def calc_spottiness(self, weighted:bool=False) -> float:
         Inspired by doi:10.1107/S1600576713029713
         Requires the azimuthal error propagation.
 
-        :param weighted: Weight the spottiness by the intensity of each ring.
+        As a rule of thumb:
+        - S < 0.05: Smooth powder pattern
+        – 0.05 < S < 0.15: Mild spottiness / texture
+        – S > 0.15 : Strongly spotty, likely with large grain size
+
+        :param weighted: Weight the spottiness by the intensity of each ring, 
+                         probably more correct but also larger values
         :return: a value that increases with the spottiness
         """
         if self.error_model != ErrorModel.AZIMUTHAL: