Add support for all data types.

All dtypes larger than 8-bits are converted to uint16 and then bit-shifted to
uint12.

skimage/filter/rank/_rank.py

@@ -17,7 +17,7 @@ References
 """
 
 import numpy as np
-from skimage import img_as_ubyte
+from skimage import img_as_ubyte, img_as_uint
 from skimage.filter.rank import _crank8, _crank16
 from skimage.filter.rank.generic import find_bitdepth
 
@@ -44,18 +44,16 @@ def _apply(func8, func16, image, selem, out, mask, shift_x, shift_y):
 
     if func8 is not None and (is_8bit or func16 is None):
         out = _apply8(func8, image, selem, out, mask, shift_x, shift_y)
-    elif image.dtype == np.uint16:
-        if func16 is None:
-            raise TypeError("Not implemented for uint16 image.")
+    else:
+        image = img_as_uint(image)
         if out is None:
             out = np.zeros(image.shape, dtype=np.uint16)
         bitdepth = find_bitdepth(image)
         if bitdepth > 11:
-            raise ValueError("Only uint16 <4096 image (12bit) supported.")
+            image = image >> 4
+            bitdepth = find_bitdepth(image)
         func16(image, selem, shift_x=shift_x, shift_y=shift_y, mask=mask,
                bitdepth=bitdepth + 1, out=out)
-    else:
-        raise TypeError("Only uint8 and uint16 image supported.")
 
     return out
 

skimage/filter/rank/tests/test_rank.py

@@ -1,7 +1,7 @@
 import numpy as np
 from numpy.testing import run_module_suite, assert_array_equal, assert_raises
 
-from skimage import img_as_ubyte
+from skimage import img_as_ubyte, img_as_uint, img_as_float
 from skimage import data, util
 from skimage.morphology import cmorph, disk
 from skimage.filter import rank
@@ -187,6 +187,24 @@ def test_compare_autolevels_16bit():
     assert_array_equal(loc_autolevel, loc_perc_autolevel)
 
 
+def test_compare_uint_vs_float():
+    # filters applied on 8-bit image ore 16-bit image (having only real 8-bit of
+    # dynamic) should be identical
+
+    # Create signed int8 image that and convert it to uint8
+    image_uint = img_as_uint(data.camera())
+    image_float = img_as_float(image_uint)
+
+    methods = ['autolevel', 'bottomhat', 'equalize', 'gradient', 'threshold',
+               'meansubtraction', 'morph_contr_enh', 'pop', 'tophat']
+
+    for method in methods:
+        func = getattr(rank, method)
+        out_u = func(image_uint, disk(3))
+        out_f = func(image_float, disk(3))
+        assert_array_equal(out_u, out_f)
+
+
 def test_compare_8bit_unsigned_vs_signed():
     # filters applied on 8-bit image ore 16-bit image (having only real 8-bit of
     # dynamic) should be identical