allow similarity computation without mask

Author: bpinsard

nipype/interfaces/nipy/utils.py

@@ -28,8 +28,8 @@ class SimilarityInputSpec(BaseInterfaceInputSpec):
 
     volume1 = File(exists=True, desc="3D volume", mandatory=True)
     volume2 = File(exists=True, desc="3D volume", mandatory=True)
-    mask1 = File(exists=True, desc="3D volume", mandatory=True)
-    mask2 = File(exists=True, desc="3D volume", mandatory=True)
+    mask1 = File(exists=True, desc="3D volume")
+    mask2 = File(exists=True, desc="3D volume")
     metric = traits.Either(traits.Enum('cc', 'cr', 'crl1', 'mi', 'nmi', 'slr'),
                           traits.Callable(),
                          desc="""str or callable
@@ -98,4 +98,4 @@ def _run_interface(self, runtime):
     def _list_outputs(self):
         outputs = self._outputs().get()
         outputs['similarity'] = self._similarity
-        return outputs
+        return outputs