Fix test: clip image that exceeded float range.

skimage/filter/tests/test_tv_denoise.py

@@ -15,6 +15,8 @@ class TestTvDenoise():
         lena = color.rgb2gray(data.lena())[:256, :256]
         # add noise to lena
         lena += 0.5 * lena.std()*np.random.randn(*lena.shape)
+        # clip noise so that it does not exceed allowed range for float images.
+        lena = np.clip(lena, 0, 1)
         # denoise
         denoised_lena = filter.tv_denoise(lena, weight=60.0)
         # which dtype?

skimage/util/dtype.py

@@ -20,7 +20,7 @@ _supported_types = (np.uint8, np.uint16, np.uint32,
                     np.float16, np.float32, np.float64)
 
 
-def _convert(image, dtype):
+def convert(image, dtype):
     """
     Convert an image to the requested data-type.
 
@@ -167,7 +167,7 @@ def img_as_float(image):
     Negative input values will be shifted to the positive domain.
 
     """
-    return _convert(image, np.float64)
+    return convert(image, np.float64)
 
 
 def img_as_uint(image):
@@ -188,7 +188,7 @@ def img_as_uint(image):
     Negative input values will be shifted to the positive domain.
 
     """
-    return _convert(image, np.uint16)
+    return convert(image, np.uint16)
 
 
 def img_as_int(image):
@@ -210,7 +210,7 @@ def img_as_int(image):
     the output image will still only have positive values.
 
     """
-    return _convert(image, np.int16)
+    return convert(image, np.int16)
 
 
 def img_as_ubyte(image):
@@ -232,4 +232,4 @@ def img_as_ubyte(image):
     the output image will still only have positive values.
 
     """
-    return _convert(image, np.uint8)
+    return convert(image, np.uint8)

skimage/util/tests/test_dtype.py

@@ -2,7 +2,7 @@ import numpy as np
 from numpy.testing import assert_equal, assert_raises
 from skimage import img_as_int, img_as_float, \
                     img_as_uint, img_as_ubyte
-from skimage.util.dtype import _convert
+from skimage.util.dtype import convert
 
 
 dtype_range = {np.uint8: (0, 255),
@@ -40,7 +40,7 @@ def test_range():
 def test_range_extra_dtypes():
     """Test code paths that are not skipped by `test_range`"""
 
-    # Add non-standard data types that are allowed by the `_convert` function.
+    # Add non-standard data types that are allowed by the `convert` function.
     dtype_range_extra = dtype_range.copy()
     dtype_range_extra.update({np.int32: (-2147483648, 2147483647),
                               np.uint32: (0, 4294967295)})
@@ -55,7 +55,7 @@ def test_range_extra_dtypes():
     for dtype_in, dt in dtype_pairs:
         imin, imax = dtype_range_extra[dtype_in]
         x = np.linspace(imin, imax, 10).astype(dtype_in)
-        y = _convert(x, dt)
+        y = convert(x, dt)
         omin, omax = dtype_range_extra[dt]
         yield _verify_range, \
               "From %s to %s" % (np.dtype(dtype_in), np.dtype(dt)), \