Revert to using xr.ufuncs

xarray/plot/plot.py

@@ -479,6 +479,11 @@ def line(self, *args, **kwargs):
 
 def _rescale_imshow_rgb(darray, vmin, vmax, robust):
     assert robust or vmin is not None or vmax is not None
+    # TODO: remove when min numpy version is bumped to 1.13
+    # There's a cyclic dependency via DataArray, so we can't import from
+    # xarray.ufuncs in global scope.
+    from xarray.ufuncs import maximum, minimum
+
     # Calculate vmin and vmax automatically for `robust=True`
     if robust:
         if vmax is None:
@@ -504,7 +509,10 @@ def _rescale_imshow_rgb(darray, vmin, vmax, robust):
     # After scaling, downcast to 32-bit float.  This substantially reduces
     # memory usage after we hand `darray` off to matplotlib.
     darray = ((darray.astype('f8') - vmin) / (vmax - vmin)).astype('f4')
-    return np.minimum(np.maximum(darray, 0), 1)
+    with warnings.catch_warnings():
+        warnings.filterwarnings('ignore', 'xarray.ufuncs',
+                                PendingDeprecationWarning)
+        return minimum(maximum(darray, 0), 1)
 
 
 def _plot2d(plotfunc):