Remove Image wrapper from io. Improve tags handling.

doc/source/api_changes.txt

@@ -1,9 +1,14 @@
+Version 0.9
+-----------
+- No longer wrap ``imread`` output in an ``Image`` class.
+
+Version 0.4
+-----------
+- Switch mask and radius arguments for ``median_filter``
+
 Version 0.3
 -----------
 - Remove ``as_grey``, ``dtype`` keyword from ImageCollection
 - Remove ``dtype`` from imread
 - Generalise ImageCollection to accept a load_func
 
-Version 0.4
------------
-- Switch mask and radius arguments for median_filter

skimage/io/_io.py

@@ -35,28 +35,33 @@ class Image(np.ndarray):
 
     These objects have tags for image metadata and IPython display protocol
     methods for image display.
-    """
 
-    tags = {'filename': '',
-            'EXIF': {},
-            'info': {}}
+    Parameters
+    ----------
+    arr : ndarray
+        Image data.
+    kwargs : Image tags as keywords
+        Specified in the form ``tag0=value``, ``tag1=value``.
+
+    Attributes
+    ----------
+    tags : dict
+        Meta-data.
+
+    """
 
     def __new__(cls, arr, **kwargs):
         """Set the image data and tags according to given parameters.
 
-        Parameters
-        ----------
-        arr : ndarray
-            Image data.
-        kwargs : Image tags as keywords
-            Specified in the form ``tag0=value``, ``tag1=value``.
-
         """
         x = np.asarray(arr).view(cls)
-        for tag, value in Image.tags.items():
-            setattr(x, tag, kwargs.get(tag, getattr(arr, tag, value)))
+        x.tags = kwargs
+
         return x
 
+    def __array_finalize__(self, obj):
+        self.tags = getattr(obj, 'tags', {})
+
     def _repr_png_(self):
         return self._repr_image_format('png')
 
@@ -147,7 +152,7 @@ def imread(fname, as_grey=False, plugin=None, flatten=None,
     if as_grey and getattr(img, 'ndim', 0) >= 3:
         img = rgb2grey(img)
 
-    return Image(img)
+    return img
 
 
 def imread_collection(load_pattern, conserve_memory=True,

skimage/io/tests/test_collection.py

@@ -57,7 +57,7 @@ class TestImageCollection():
     def test_getitem(self):
         num = len(self.collection)
         for i in range(-num, num):
-            assert type(self.collection[i]) is ioImage
+            assert type(self.collection[i]) is np.ndarray
         assert_array_almost_equal(self.collection[0],
                                   self.collection[-num])
 

skimage/io/tests/test_pil.py

@@ -6,7 +6,8 @@ from numpy.testing.decorators import skipif
 from tempfile import NamedTemporaryFile
 
 from skimage import data_dir
-from skimage.io import imread, imsave, use_plugin, reset_plugins
+from skimage.io import (imread, imsave, use_plugin, reset_plugins,
+                        Image as ioImage)
 from skimage._shared.six.moves import StringIO
 
 
@@ -83,7 +84,7 @@ def test_imread_uint16():
 @skipif(not PIL_available)
 def test_repr_png():
     img_path = os.path.join(data_dir, 'camera.png')
-    original_img = imread(img_path)
+    original_img = ioImage(imread(img_path))
     original_img_str = original_img._repr_png_()
 
     with NamedTemporaryFile(suffix='.png') as temp_png: