BUG: Fix homography.

skimage/transform/_warps.py

@@ -1,5 +1,6 @@
 import numpy as np
-from ._geometric import warp, SimilarityTransform, AffineTransform
+from ._geometric import (warp, SimilarityTransform, AffineTransform,
+                         ProjectiveTransform)
 
 
 def resize(image, output_shape, order=1, mode='constant', cval=0.):

skimage/transform/tests/test_warps.py

@@ -5,7 +5,7 @@ from scipy.ndimage import map_coordinates
 from skimage.transform import (warp, warp_coords, rotate, resize,
                                AffineTransform,
                                ProjectiveTransform,
-                               SimilarityTransform)
+                               SimilarityTransform, homography)
 from skimage import transform as tf, data, img_as_float
 from skimage.color import rgb2gray
 
@@ -34,11 +34,15 @@ def test_homography():
                   [0,               0,             1]])
 
     x90 = warp(x,
-            inverse_map=ProjectiveTransform(M).inverse,
-            order=1)
+               inverse_map=ProjectiveTransform(M).inverse,
+               order=1)
     assert_array_almost_equal(x90, np.rot90(x))
 
 
+def test_homography_basic():
+    homography(np.random.random((25, 25)), np.eye(3))
+
+
 def test_fast_homography():
     img = rgb2gray(data.lena()).astype(np.uint8)
     img = img[:, :100]