Merge pull request #1392 from jmetz/threshold_li

Update threshold_li

CONTRIBUTORS.txt

@@ -206,3 +206,7 @@
 
 - Kevin Keraudren
   Fix and test for feature.peak_local_max
+    
+Jeremy Metz
+  - Adaptation of ImageJ Autothresholder.Li, fixed Qhull error QH6228   
+

skimage/filters/thresholding.py

@@ -316,8 +316,8 @@ def threshold_li(image):
     Returns
     -------
     threshold : float
-        Upper threshold value. All pixels intensities that less or equal of
-        this value assumed as foreground.
+        Upper threshold value. All pixels intensities more than
+        this value are assumed to be foreground.
 
     References
     ----------
@@ -331,14 +331,12 @@ def threshold_li(image):
            http://citeseer.ist.psu.edu/sezgin04survey.html
     .. [4] ImageJ AutoThresholder code, http://fiji.sc/wiki/index.php/Auto_Threshold
 
-    Adapted for skimage by J. Metz from ImageJ plugin by G.Landini
-
     Examples
     --------
     >>> from skimage.data import camera
     >>> image = camera()
     >>> thresh = threshold_li(image)
-    >>> binary = image <= thresh
+    >>> binary = image > thresh
     """
     # Requires positive image (because of log(mean))
     offset = image.min()