BUG: Activate displaced detector padding in iterative FDK

Set displaced detector filter in iterative FDK reconstruction filter to true by default, to avoid dark hole in reconstructed image from displaced detector projections.

include/rtkIterativeFDKConeBeamReconstructionFilter.hxx

@@ -52,7 +52,7 @@ IterativeFDKConeBeamReconstructionFilter<TInputImage, TOutputImage, TFFTPrecisio
   m_DivideFilter = DivideFilterType::New();
 
   // Filter parameters
-  m_DisplacedDetectorFilter->SetPadOnTruncatedSide(false);
+  m_DisplacedDetectorFilter->SetPadOnTruncatedSide(true);
   m_DisableDisplacedDetectorFilter = false;
 }