1 files changed, 2 insertions, 2 deletions
diff --git a/Wrappers/Python/ccpi/astra/processors/AstraBackProjectorMC.py b/Wrappers/Python/ccpi/astra/processors/AstraBackProjectorMC.py
index 84932b6..ef8fe5d 100644
--- a/Wrappers/Python/ccpi/astra/processors/AstraBackProjectorMC.py
+++ b/Wrappers/Python/ccpi/astra/processors/AstraBackProjectorMC.py
@@ -23,7 +23,7 @@ class AstraBackProjectorMC(AstraBackProjector):
             raise ValueError("Expected input dimensions is 2 or 3, got {0}"\
                              .format(dataset.number_of_dimensions))
     
-    def process(self, out):
+    def process(self, out=None):
         DATA = self.get_input()
         
         IM = ImageData(geometry=self.volume_geometry)
@@ -43,4 +43,4 @@ class AstraBackProjectorMC(AstraBackProjector):
         if out is None:
             return ret
         else:
-            out.fill(ret)
-\ No newline at end of file
+            out.fill(ret)