From 741d6fda95e7c1c94f7ff06a7428603805c971d8 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Fran=C3=A7ois=20Boulogne?= <fboulogne sciunto org>
Date: Wed, 2 Oct 2013 17:44:05 +0200
Subject: [PATCH] PEP8: comparison

---
 skimage/io/video.py                   | 2 +-
 skimage/morphology/greyreconstruct.py | 2 +-
 skimage/morphology/watershed.py       | 8 ++++----
 3 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/skimage/io/video.py b/skimage/io/video.py
index 6cb1a8e9..003a1f53 100644
--- a/skimage/io/video.py
+++ b/skimage/io/video.py
@@ -256,7 +256,7 @@ class Video(object):
         Backend to use.
     """
     def __init__(self, source=None, size=None, sync=False, backend=None):
-        if backend == None:
+        if backend is None:
             # select backend that is available
             if gstreamer_available:
                 self.video = GstVideo(source, size, sync)
diff --git a/skimage/morphology/greyreconstruct.py b/skimage/morphology/greyreconstruct.py
index 17455b55..3fffd28e 100644
--- a/skimage/morphology/greyreconstruct.py
+++ b/skimage/morphology/greyreconstruct.py
@@ -133,7 +133,7 @@ def reconstruction(seed, mask, method='dilation', selem=None, offset=None):
     else:
         selem = selem.copy()
 
-    if offset == None:
+    if offset is None:
         if not all([d % 2 == 1 for d in selem.shape]):
             ValueError("Footprint dimensions must all be odd")
         offset = np.array([d // 2 for d in selem.shape])
diff --git a/skimage/morphology/watershed.py b/skimage/morphology/watershed.py
index fbd63281..097e3129 100644
--- a/skimage/morphology/watershed.py
+++ b/skimage/morphology/watershed.py
@@ -124,13 +124,13 @@ def watershed(image, markers, connectivity=None, offset=None, mask=None):
     separate overlapping spheres.
     """
 
-    if connectivity == None:
+    if connectivity is None:
         c_connectivity = scipy.ndimage.generate_binary_structure(image.ndim, 1)
     else:
         c_connectivity = np.array(connectivity, bool)
         if c_connectivity.ndim != image.ndim:
             raise ValueError("Connectivity dimension must be same as image")
-    if offset == None:
+    if offset is None:
         if any([x % 2 == 0 for x in c_connectivity.shape]):
             raise ValueError("Connectivity array must have an unambiguous "
                     "center")
@@ -162,7 +162,7 @@ def watershed(image, markers, connectivity=None, offset=None, mask=None):
                          "as image (ndim=%d)" % (c_markers.ndim, c_image.ndim))
     if c_markers.shape != c_image.shape:
         raise ValueError("image and markers must have the same shape")
-    if mask != None:
+    if mask is not None:
         c_mask = np.ascontiguousarray(mask, dtype=bool)
         if c_mask.ndim != c_markers.ndim:
             raise ValueError("mask must have same # of dimensions as image")
@@ -398,7 +398,7 @@ def _slow_watershed(image, markers, connectivity=8, mask=None):
                 continue
             if labels[x, y]:
                 continue
-            if mask != None and not mask[x, y]:
+            if mask is not None and not mask[x, y]:
                 continue
             # label the pixel
             labels[x, y] = pix_label