diff --git a/pyqtgraph/graphicsItems/HistogramLUTItem.py b/pyqtgraph/graphicsItems/HistogramLUTItem.py
index 38f1e5b4..24a1dce8 100644
--- a/pyqtgraph/graphicsItems/HistogramLUTItem.py
+++ b/pyqtgraph/graphicsItems/HistogramLUTItem.py
@@ -165,7 +165,7 @@ class HistogramLUTItem(GraphicsWidget):
         """
         self.imageItem = weakref.ref(img)
         img.sigImageChanged.connect(self.imageChanged)
-        img.setLookupTable(self.getLookupTable)  ## send function pointer, not the result
+        self._setImageLookupTable()
         self.regionChanged()
         self.imageChanged(autoLevel=True)
         
@@ -174,14 +174,17 @@ class HistogramLUTItem(GraphicsWidget):
     
     def gradientChanged(self):
         if self.imageItem() is not None:
-            if self.gradient.isLookupTrivial():
-                self.imageItem().setLookupTable(None) #lambda x: x.astype(np.uint8))
-            else:
-                self.imageItem().setLookupTable(self.getLookupTable)  ## send function pointer, not the result
+            self._setImageLookupTable()
             
         self.lut = None
         self.sigLookupTableChanged.emit(self)
 
+    def _setImageLookupTable(self):
+        if self.gradient.isLookupTrivial():
+            self.imageItem().setLookupTable(None) #lambda x: x.astype(np.uint8))
+        else:
+            self.imageItem().setLookupTable(self.getLookupTable)  ## send function pointer, not the result
+
     def getLookupTable(self, img=None, n=None, alpha=None):
         """Return a lookup table from the color gradient defined by this 
         HistogramLUTItem.
@@ -341,6 +344,7 @@ class HistogramLUTItem(GraphicsWidget):
         }
     
     def restoreState(self, state):
-        self.setLevelMode(state['mode'])
+        if 'mode' in state:
+            self.setLevelMode(state['mode'])
         self.gradient.restoreState(state['gradient'])
         self.setLevels(*state['levels'])