Clean up opencv namespace and imports.

scikits/image/opencv/__init__.py

@@ -1,14 +1,11 @@
-import ctypes
-import sys
-
 from opencv_constants import *
 
 # Note: users should be able to import this module even if
 # the extensions are uncompiled or the opencv libraries unavailable.
 # In that case, the opencv functionality is simply unavailable.
 
-cv = None
-cxcore = None
+loaded = False
+
 try:
     from opencv_cv import *
 except ImportError:
@@ -18,7 +15,12 @@ python setup.py build_ext -i
 
 in the source directory to build in-place.  Please refer to INSTALL.txt
 for further detail."""
-
 except RuntimeError:
     # Libraries could not be loaded
     print "*** Skipping import of OpenCV functions."
+    del (opencv_backend, opencv_cv)
+else:
+    loaded = True
+
+del opencv_constants
+

scikits/image/opencv/tests/test_opencv_cv.py

@@ -11,13 +11,13 @@ with warnings.catch_warnings():
     warnings.simplefilter("ignore")
     from scikits.image.opencv import *
 
-opencv_skip = dec.skipif(cv is None,
+opencv_skip = dec.skipif(not loaded,
                          'OpenCV libraries not found')
 
 class OpenCVTest:
     lena_RGB_U8 = np.load(os.path.join(data_dir, 'lena_RGB_U8.npy'))
     lena_GRAY_U8 = np.load(os.path.join(data_dir, 'lena_GRAY_U8.npy'))
-    
+
 
 class TestSobel(OpenCVTest):
     @opencv_skip