From d74295c7f1cf98af31abaa2fc4033b5269923ae1 Mon Sep 17 00:00:00 2001
From: Stefan van der Walt <stefan@sun.ac.za>
Date: Mon, 26 Dec 2011 01:53:59 -0800
Subject: [PATCH] DOC: Explain why bincount is used to histogram integer
 arrays.

---
 skimage/exposure/exposure.py | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/skimage/exposure/exposure.py b/skimage/exposure/exposure.py
index d120b386..42a60dbf 100644
--- a/skimage/exposure/exposure.py
+++ b/skimage/exposure/exposure.py
@@ -28,6 +28,8 @@ def histogram(image, nbins=256):
     bin_centers : array
         The values at the center of the bins.
     """
+
+    # For integer types, histogramming with bincount is more efficient.
     if np.issubdtype(image.dtype, np.integer):
         offset = 0
         if np.min(image) < 0: