-BBTK_INPUT(VolumeRendering,In4,"Image to create the volume rendering",vtkImageData*,"");
-BBTK_INPUT(VolumeRendering,Renderer,"Image to create the volume rendering",vtkRenderer*,"");
+BBTK_INPUT(VolumeRendering,Renderer,"Renderer",vtkRenderer*,"");
+BBTK_OUTPUT(VolumeRendering,Out0,"Output resulting image",vtkImageData*,"");
+BBTK_OUTPUT(VolumeRendering,Out1,"Output resulting image",vtkImageData*,"");
+BBTK_OUTPUT(VolumeRendering,Out2,"Output resulting image",vtkImageData*,"");
+BBTK_OUTPUT(VolumeRendering,Out3,"Output resulting image",vtkImageData*,"");