Make sure rgb2gray output is contiguous

skimage/color/colorconv.py

@@ -709,7 +709,7 @@ def rgb2gray(rgb):
     """
 
     if rgb.ndim == 2:
-        return rgb
+        return np.ascontiguousarray(rgb)
 
     rgb = _prepare_colorarray(rgb)
 
@@ -719,6 +719,7 @@ def rgb2gray(rgb):
 
     return gray
 
+
 rgb2grey = rgb2gray
 
 

skimage/color/tests/test_colorconv.py

@@ -226,6 +226,11 @@ class TestColorconv(TestCase):
 
         assert_equal(g.shape, (1, 1))
 
+    def test_rgb2grey_contiguous(self):
+        x = np.random.rand(10, 10, 3)
+        assert rgb2grey(x).flags["C_CONTIGUOUS"]
+        assert rgb2grey(x[:5, :5]).flags["C_CONTIGUOUS"]
+
     def test_rgb2grey_on_grey(self):
         rgb2grey(np.random.rand(5, 5))