diff --git a/pyqtgraph/graphicsItems/ImageItem.py b/pyqtgraph/graphicsItems/ImageItem.py
index 3d45ad77..9588c586 100644
--- a/pyqtgraph/graphicsItems/ImageItem.py
+++ b/pyqtgraph/graphicsItems/ImageItem.py
@@ -214,7 +214,8 @@ class ImageItem(GraphicsObject):
         border             Sets the pen used when drawing the image border. Default is None.
         autoDownsample     (bool) If True, the image is automatically downsampled to match the
                            screen resolution. This improves performance for large images and 
-                           reduces aliasing.
+                           reduces aliasing. If autoDownsample is not specified, then ImageItem will
+                           choose whether to downsample the image based on its size.
         =================  =========================================================================
         
         
diff --git a/pyqtgraph/graphicsItems/PlotCurveItem.py b/pyqtgraph/graphicsItems/PlotCurveItem.py
index d66a8a99..fac9ee57 100644
--- a/pyqtgraph/graphicsItems/PlotCurveItem.py
+++ b/pyqtgraph/graphicsItems/PlotCurveItem.py
@@ -132,6 +132,8 @@ class PlotCurveItem(GraphicsObject):
             if any(np.isinf(b)):
                 mask = np.isfinite(d)
                 d = d[mask]
+                if len(d) == 0:
+                    return (None, None)
                 b = (d.min(), d.max())
                 
         elif frac <= 0.0:
@@ -173,7 +175,7 @@ class PlotCurveItem(GraphicsObject):
         if self._boundingRect is None:
             (xmn, xmx) = self.dataBounds(ax=0)
             (ymn, ymx) = self.dataBounds(ax=1)
-            if xmn is None:
+            if xmn is None or ymn is None:
                 return QtCore.QRectF()
             
             px = py = 0.0
diff --git a/pyqtgraph/multiprocess/processes.py b/pyqtgraph/multiprocess/processes.py
index c7e4a80c..02f259e5 100644
--- a/pyqtgraph/multiprocess/processes.py
+++ b/pyqtgraph/multiprocess/processes.py
@@ -321,9 +321,14 @@ class ForkedProcess(RemoteEventHandler):
         #os.kill(pid, 9)  
         try:
             self.close(callSync='sync', timeout=timeout, noCleanup=True)  ## ask the child process to exit and require that it return a confirmation.
-            os.waitpid(self.childPid, 0)
         except IOError:  ## probably remote process has already quit
             pass  
+        
+        try:
+            os.waitpid(self.childPid, 0)
+        except OSError:  ## probably remote process has already quit
+            pass
+        
         self.hasJoined = True
 
     def kill(self):