BUG: Fix division error for Python 3

skimage/morphology/greyreconstruct.py

@@ -133,7 +133,7 @@ def reconstruction(seed, mask, method='dilation', selem=None, offset=None):
     if offset == 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])
+        offset = np.array([d // 2 for d in selem.shape])
     # Cross out the center of the selem
     selem[[slice(d, d + 1) for d in offset]] = False