diff --git a/skimage/color/colorconv.py b/skimage/color/colorconv.py
index e7e7720a..6260d9f5 100644
--- a/skimage/color/colorconv.py
+++ b/skimage/color/colorconv.py
@@ -51,8 +51,7 @@ __all__ = ['convert_colorspace', 'rgb2hsv', 'hsv2rgb', 'rgb2xyz', 'xyz2rgb',
            'rgb_from_bex', 'bex_from_rgb', 'rgb_from_rbd', 'rbd_from_rgb',
            '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_gray_2d'
+           'rgb_from_ahx', 'ahx_from_rgb', 'rgb_from_hpx', 'hpx_from_rgb'
            ]
 
 __docformat__ = "restructuredtext en"
@@ -63,40 +62,6 @@ from ..util import dtype
 from skimage._shared.utils import deprecated
 
 
-def is_rgb(image):
-    """Test whether the image is RGB or RGBA.
-
-    Parameters
-    ----------
-    image : ndarray
-        Input 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).
-
-    Parameters
-    ----------
-    image : ndarray
-        Input image.
-
-    """
-    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.
 
@@ -663,9 +628,9 @@ def gray2rgb(image):
         If the input is not 2-dimensional.
 
     """
-    if is_rgb(image):
+    if np.squeeze(image).ndim == 3 and image.shape[2] in (3, 4):
         return image
-    elif is_gray(image):
+    elif np.squeeze(image).ndim == 2:
         return np.dstack((image, image, image))
     else:
         raise ValueError("Input image expected to be RGB, RGBA or gray.")
diff --git a/skimage/color/tests/test_colorconv.py b/skimage/color/tests/test_colorconv.py
index 2cdde1fe..d31ef34c 100644
--- a/skimage/color/tests/test_colorconv.py
+++ b/skimage/color/tests/test_colorconv.py
@@ -28,8 +28,7 @@ from skimage.color import (
     convert_colorspace,
     rgb2grey, gray2rgb,
     xyz2lab, lab2xyz,
-    lab2rgb, rgb2lab,
-    is_rgb, is_gray, is_gray_2d
+    lab2rgb, rgb2lab
     )
 
 from skimage import data_dir, data
@@ -252,16 +251,5 @@ def test_gray2rgb_rgb():
     assert_equal(x, y)
 
 
-def test_is_rgb():
-    color = data.lena()
-    gray = data.camera()
-
-    assert is_rgb(color)
-    assert not is_gray(color)
-
-    assert is_gray(gray)
-    assert not is_gray(color)
-
-
 if __name__ == "__main__":
     run_module_suite()