Create helper function for image conversion

skimage/transform/_geometric.py

@@ -995,6 +995,18 @@ def warp_coords(coord_map, shape, dtype=np.float64):
     return coords
 
 
+def _convert_warp_input(image, keep_range):
+    """Convert input image to double image with the appropriate range."""
+    if keep_range:
+        image = image.astype(np.double)
+    else:
+        if image.dtype == np.double:
+            image = rescale_intensity(image)
+        else:
+            image = img_as_float(image)
+    return image
+
+
 def _clip_warp_output(input_image, output_image, clip, mode, order, cval):
     """Clip output image to range of values of input image, considering the
     parameters of a call to warp.
@@ -1146,13 +1158,7 @@ def warp(image, inverse_map=None, map_args={}, output_shape=None, order=1,
 
     """
 
-    if keep_range:
-        image = image.astype(np.double)
-    else:
-        if image.dtype == np.double:
-            image = rescale_intensity(image)
-        else:
-            image = img_as_float(image)
+    image = _convert_warp_input(image, keep_range)
 
     input_shape = np.array(image.shape)
 

skimage/transform/_warps.py

@@ -1,11 +1,9 @@
 import numpy as np
 from scipy import ndimage
 
-from ..util import img_as_float
-from ..exposure import rescale_intensity
 from ..measure import block_reduce
 from ._geometric import (warp, SimilarityTransform, AffineTransform,
-                         _clip_warp_output)
+                         _convert_warp_input, _clip_warp_output)
 
 
 def resize(image, output_shape, order=1, mode='constant', cval=0, clip=True,
@@ -81,13 +79,7 @@ def resize(image, output_shape, order=1, mode='constant', cval=0, clip=True,
 
         coord_map = np.array([map_rows, map_cols, map_dims])
 
-        if keep_range:
-            image = image.astype(np.double)
-        else:
-            if image.dtype == np.double:
-                image = rescale_intensity(image)
-            else:
-                image = img_as_float(image)
+        image = _convert_warp_input(image, keep_range)
 
         out = ndimage.map_coordinates(image, coord_map, order=order,
                                       mode=mode, cval=cval)