Rename keep_range to preserve_range, fix test cases

skimage/transform/_geometric.py

@@ -995,16 +995,12 @@ def warp_coords(coord_map, shape, dtype=np.float64):
     return coords
 
 
-def _convert_warp_input(image, keep_range):
+def _convert_warp_input(image, preserve_range):
     """Convert input image to double image with the appropriate range."""
-    if keep_range:
+    if preserve_range:
         image = image.astype(np.double)
     else:
-        if image.dtype == np.double:
-            image = rescale_intensity(image)
-            image = np.atleast_2d(image)
-        else:
-            image = img_as_float(image)
+        image = img_as_float(image)
     return image
 
 
@@ -1027,7 +1023,7 @@ def _clip_warp_output(input_image, output_image, clip, mode, order, cval):
 
 
 def warp(image, inverse_map=None, map_args={}, output_shape=None, order=1,
-         mode='constant', cval=0., clip=True, keep_range=False):
+         mode='constant', cval=0., clip=True, preserve_range=False):
     """Warp an image according to a given coordinate transformation.
 
     Parameters
@@ -1090,7 +1086,7 @@ def warp(image, inverse_map=None, map_args={}, output_shape=None, order=1,
         Whether to clip the output to the range of values of the input image.
         This is enabled by default, since higher order interpolation may
         produce values outside the given input range.
-    keep_range : bool, optional
+    preserve_range : bool, optional
         Whether to keep the original range of values. Otherwise, the input
         image is converted according to the conventions of `img_as_float`.
 
@@ -1159,7 +1155,7 @@ def warp(image, inverse_map=None, map_args={}, output_shape=None, order=1,
 
     """
 
-    image = _convert_warp_input(image, keep_range)
+    image = _convert_warp_input(image, preserve_range)
 
     input_shape = np.array(image.shape)
 

skimage/transform/_warps.py

@@ -7,7 +7,7 @@ from ._geometric import (warp, SimilarityTransform, AffineTransform,
 
 
 def resize(image, output_shape, order=1, mode='constant', cval=0, clip=True,
-           keep_range=False):
+           preserve_range=False):
     """Resize image to match a certain size.
 
     Performs interpolation to up-size or down-size images. For down-sampling
@@ -45,7 +45,7 @@ def resize(image, output_shape, order=1, mode='constant', cval=0, clip=True,
         Whether to clip the output to the range of values of the input image.
         This is enabled by default, since higher order interpolation may
         produce values outside the given input range.
-    keep_range : bool, optional
+    preserve_range : bool, optional
         Whether to keep the original range of values. Otherwise, the input
         image is converted according to the conventions of `img_as_float`.
 
@@ -79,7 +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])
 
-        image = _convert_warp_input(image, keep_range)
+        image = _convert_warp_input(image, preserve_range)
 
         out = ndimage.map_coordinates(image, coord_map, order=order,
                                       mode=mode, cval=cval)
@@ -99,13 +99,13 @@ def resize(image, output_shape, order=1, mode='constant', cval=0, clip=True,
         tform.estimate(src_corners, dst_corners)
 
         out = warp(image, tform, output_shape=output_shape, order=order,
-                   mode=mode, cval=cval, clip=clip, keep_range=keep_range)
+                   mode=mode, cval=cval, clip=clip, preserve_range=preserve_range)
 
     return out
 
 
 def rescale(image, scale, order=1, mode='constant', cval=0, clip=True,
-            keep_range=False):
+            preserve_range=False):
     """Scale image by a certain factor.
 
     Performs interpolation to upscale or down-scale images. For down-sampling
@@ -141,7 +141,7 @@ def rescale(image, scale, order=1, mode='constant', cval=0, clip=True,
         Whether to clip the output to the range of values of the input image.
         This is enabled by default, since higher order interpolation may
         produce values outside the given input range.
-    keep_range : bool, optional
+    preserve_range : bool, optional
         Whether to keep the original range of values. Otherwise, the input
         image is converted according to the conventions of `img_as_float`.
 
@@ -168,11 +168,11 @@ def rescale(image, scale, order=1, mode='constant', cval=0, clip=True,
     output_shape = (rows, cols)
 
     return resize(image, output_shape, order=order, mode=mode, cval=cval,
-                  clip=clip, keep_range=keep_range)
+                  clip=clip, preserve_range=preserve_range)
 
 
 def rotate(image, angle, resize=False, center=None, order=1, mode='constant',
-           cval=0, clip=True, keep_range=False):
+           cval=0, clip=True, preserve_range=False):
     """Rotate image by a certain angle around its center.
 
     Parameters
@@ -209,7 +209,7 @@ def rotate(image, angle, resize=False, center=None, order=1, mode='constant',
         Whether to clip the output to the range of values of the input image.
         This is enabled by default, since higher order interpolation may
         produce values outside the given input range.
-    keep_range : bool, optional
+    preserve_range : bool, optional
         Whether to keep the original range of values. Otherwise, the input
         image is converted according to the conventions of `img_as_float`.
 
@@ -258,7 +258,7 @@ def rotate(image, angle, resize=False, center=None, order=1, mode='constant',
         tform = tform4 + tform
 
     return warp(image, tform, output_shape=output_shape, order=order,
-                mode=mode, cval=cval, clip=clip, keep_range=keep_range)
+                mode=mode, cval=cval, clip=clip, preserve_range=preserve_range)
 
 
 def downscale_local_mean(image, factors, cval=0, clip=True):
@@ -323,7 +323,7 @@ def _swirl_mapping(xy, center, rotation, strength, radius):
 
 def swirl(image, center=None, strength=1, radius=100, rotation=0,
           output_shape=None, order=1, mode='constant', cval=0, clip=True,
-          keep_range=False):
+          preserve_range=False):
     """Perform a swirl transformation.
 
     Parameters
@@ -363,7 +363,7 @@ def swirl(image, center=None, strength=1, radius=100, rotation=0,
         Whether to clip the output to the range of values of the input image.
         This is enabled by default, since higher order interpolation may
         produce values outside the given input range.
-    keep_range : bool, optional
+    preserve_range : bool, optional
         Whether to keep the original range of values. Otherwise, the input
         image is converted according to the conventions of `img_as_float`.
 
@@ -379,4 +379,4 @@ def swirl(image, center=None, strength=1, radius=100, rotation=0,
 
     return warp(image, _swirl_mapping, map_args=warp_args,
                 output_shape=output_shape, order=order, mode=mode, cval=cval,
-                clip=clip, keep_range=keep_range)
+                clip=clip, preserve_range=preserve_range)

skimage/transform/tests/test_warps.py

@@ -269,14 +269,19 @@ def test_slow_warp_nonint_oshape():
 def test_keep_range():
     image = np.linspace(0, 2, 25).reshape(5, 5)
 
-    out = rescale(image, 2, keep_range=False, clip=True, order=0)
-    assert out.min() == 0
-    assert out.max() == 1
-
-    out = rescale(image, 2, keep_range=True, clip=True, order=0)
+    out = rescale(image, 2, preserve_range=False, clip=True, order=0)
     assert out.min() == 0
     assert out.max() == 2
 
+    out = rescale(image, 2, preserve_range=True, clip=True, order=0)
+    assert out.min() == 0
+    assert out.max() == 2
+
+    out = rescale(image.astype(np.uint8), 2, preserve_range=False,
+                  clip=True, order=0)
+    assert out.min() == 0
+    assert out.max() == 2 / 255.0
+
 
 
 if __name__ == "__main__":