Deprecating is_gray and replacing it with is_gray_2d

skimage/color/colorconv.py

@@ -52,7 +52,7 @@ __all__ = ['convert_colorspace', 'rgb2hsv', 'hsv2rgb', 'rgb2xyz', 'xyz2rgb',
            'rgb_from_gdx', 'gdx_from_rgb', 'rgb_from_hax', 'hax_from_rgb',
            'rgb_from_bro', 'bro_from_rgb', 'rgb_from_bpx', 'bpx_from_rgb',
            'rgb_from_ahx', 'ahx_from_rgb', 'rgb_from_hpx', 'hpx_from_rgb',
-           'is_rgb', 'is_gray'
+           'is_rgb', 'is_gray', 'is_gray_2d'
            ]
 
 __docformat__ = "restructuredtext en"
@@ -60,6 +60,7 @@ __docformat__ = "restructuredtext en"
 import numpy as np
 from scipy import linalg
 from ..util import dtype
+from skimage._shared.utils import deprecated
 
 
 def is_rgb(image):
@@ -73,7 +74,7 @@ def is_rgb(image):
     """
     return (image.ndim == 3 and image.shape[2] in (3, 4))
 
-
+@deprecated('is_gray_2d')
 def is_gray(image):
     """Test whether the image is gray (i.e. has only one color band).
 
@@ -83,8 +84,18 @@ def is_gray(image):
         Input image.
 
     """
-    return image.ndim == 2
+    return is_gray_2d(image)
 
+def is_gray_2d(image):
+    """Test whether the image is 2d and grayscale.
+
+    Parameters
+    ----------
+    image : ndarray
+        Input image.
+
+    """
+    return np.squeeze(image).ndim == 2
 
 def convert_colorspace(arr, fromspace, tospace):
     """Convert an image array to a new color space.

skimage/color/tests/test_colorconv.py

@@ -29,7 +29,7 @@ from skimage.color import (
     rgb2grey, gray2rgb,
     xyz2lab, lab2xyz,
     lab2rgb, rgb2lab,
-    is_rgb, is_gray
+    is_rgb, is_gray, is_gray_2d
     )
 
 from skimage import data_dir, data
@@ -232,19 +232,16 @@ class TestColorconv(TestCase):
         assert_array_almost_equal(lab2rgb(rgb2lab(img_rgb)), img_rgb)
 
 def test_gray2rgb():
-    x = np.array([0, 0.5, 1])
-    assert_raises(ValueError, gray2rgb, x)
-
-    x = x.reshape((3, 1))
+    x = np.array([[0, 0.5, 1], [0, 0.5, 1]])
     y = gray2rgb(x)
 
-    assert_equal(y.shape, (3, 1, 3))
+    assert_equal(y.shape, (2, 3, 3))
     assert_equal(y.dtype, x.dtype)
 
-    x = np.array([[0, 128, 255]], dtype=np.uint8)
+    x = np.array([[0, 128], [128, 255], [255, 0]], dtype=np.uint8)
     z = gray2rgb(x)
 
-    assert_equal(z.shape, (1, 3, 3))
+    assert_equal(z.shape, (3, 2, 3))
     assert_equal(z[..., 0], x)
     assert_equal(z[0, 1, :], [128, 128, 128])