Fix bug in binary dilation and test case

skimage/morphology/binary.py

@@ -65,7 +65,7 @@ def binary_dilation(image, selem, out=None):
     """
 
     conv = ndimage.convolve(image > 0, selem, output=out,
-                            mode='constant', cval=1)
+                            mode='constant', cval=0)
     if conv is not None:
         out = conv
     return np.not_equal(out, 0, out=out)

skimage/morphology/tests/test_grey.py

@@ -10,7 +10,7 @@ from skimage.morphology import binary, grey, selem
 
 
 lena = np.load(os.path.join(data_dir, 'lena_GRAY_U8.npy'))
-bw_lena = lena > 0.4
+bw_lena = lena > 100
 
 
 class TestMorphology():