Update the README with some warning hints

Update the readme with some warning hints

Tweak README

Tweak README

Fix preferred plugins test

Pep8 fix

Remove imshow from PIL plugin

Fix spelling

Tweak readme

doc/README.md

@@ -3,3 +3,16 @@ To build docs, run `make` in this directory. `make help` lists all targets.
 
 ## Requirements ##
 Sphinx is needed to build doc. Install with `pip install sphinx`.
+
+## Fixing Warnings ##
+
+- "citation not found: R###"
+  $ cd doc/build; grep -rin R### .
+  There is probably an underscore after the reference (e.g. [1]_)
+
+- "Duplicate citation R###, other instance in...""
+  There is probably a [2] without a [1] in one of
+  the docstrings
+
+- Make sure to use pre-sphinxification paths to images
+  (not the _images directory)

skimage/io/_plugins/pil_plugin.py

@@ -260,20 +260,3 @@ def imsave(fname, arr, format_str=None):
 
     img = ndarray_to_pil(arr, format_str=format_str)
     img.save(fname, format=format_str)
-
-
-def imshow(arr):
-    """Display an image, using PIL's default display command.
-
-    Parameters
-    ----------
-    arr : ndarray
-       Image to display.  Images of dtype float are assumed to be in
-       [0, 1].  Images of dtype uint8 are in [0, 255].
-
-    """
-    Image.fromarray(img_as_ubyte(arr)).show()
-
-
-def _app_show():
-    pass

skimage/io/tests/test_plugin.py

@@ -93,15 +93,18 @@ def test_available():
 
 
 def test_load_preferred_plugins_all():
-    from skimage.io._plugins import pil_plugin
+    from skimage.io._plugins import pil_plugin, matplotlib_plugin
 
     with protect_preferred_plugins():
-        manage_plugins.preferred_plugins = {'all': ['pil']}
+        manage_plugins.preferred_plugins = {'all': ['pil'],
+                                            'imshow': ['matplotlib']}
         manage_plugins.reset_plugins()
 
-        for plugin_type in ('imread', 'imsave', 'imshow'):
+        for plugin_type in ('imread', 'imsave'):
             plug, func = manage_plugins.plugin_store[plugin_type][0]
             assert func == getattr(pil_plugin, plugin_type)
+        plug, func = manage_plugins.plugin_store['imshow'][0]
+        assert func == getattr(matplotlib_plugin, 'imshow')
 
 
 def test_load_preferred_plugins_imread():