[Insight-users] Bug in CastImageFilter?

[Mark Hastenteufel]

Hi Jim,

you're right. When calling UpdateLargestPossibleRegion()
everything works fine.

Isn't it possible to check in the Update() method
if the input has been changed and calling 
UpdateLargestPossibleRegion() internally?

Mark



"Miller, James V (Research)" schrieb:
> 
> This is a standard problem in the pipeline mechanism.
> 
> The issue is when Update() is called the first time, no
> RequestedRegion is set in the pipeline so it defaults to
> setting the RequestedRegion to the LargestPossibleRegion.
> 
> When you swap the input to the CastImageFilter and call
> Update() a second time, the pipeline (incorrectly) assumes
> that you want to update the same RequestedRegion that you
> asked for (implicitly) the first time.  But you did not want
> to update the same RequestedRegion, but rather, you wanted to
> update a "new" RequestedRegion that matches the size of the image
> coming from the pyramid.
> 
> The quick fix is to change the call to Update() in your loop
> to UpdateLargestPossibleRegion().
> 
> Basically, there is currently no way for the pipeline to know
> that the upstream data is not the same size as it used to be.
> 
> I hope to add some type of "flush" mechanism which will return
> a pipeline to its initial state so a user can change a input
> upstream, flush the pipeline, and have an Update() do what a
> user would expect.
> 
> Jim
> 
> > -----Original Message-----
> > From: Mark Hastenteufel [mailto:M.Hastenteufel@DKFZ-Heidelberg.de]
> > Sent: Sunday, February 09, 2003 1:11 PM
> > To: insight-users@public.kitware.com
> > Subject: [Insight-users] Bug in CastImageFilter?
> >
> >
> > Hi!
> >
> > I've found a strange behaviour in itk::CastImageFilter. I've
> > implemented a simple program which produces an image
> > pyramid.
> > The images on the respective level are written out to disk. The
> > images are converted from float (internal type of PyramidFilter)
> > to short using an ikt::CastImageFilter.
> >
> >
> > Typedef's:
> >
> >         typedef itk::Image<short,2> TInputImage2;
> >         typedef itk::Image<double,2> TOutputImage;
> >         typedef itk::MultiResolutionPyramidImageFilter< TOutputImage,
> > TOutputImage > PyramidType;
> >         typedef itk::CastImageFilter< TOutputImage,TInputImage2 >
> > CastFilterType;
> >
> >
> > If using the following code:
> >
> >
> >   myPyramid->SetNumberOfLevels(noLevels);
> >   myPyramid->SetInput( image );
> >   myPyramid->UpdateLargestPossibleRegion();
> >
> >   CastFilterType::Pointer myCaster = CastFilterType::New();
> >   for (int i=0 ; i<noLevels ; i++)
> >   {
> >     myCaster->SetInput( myPyramid->GetOutput(i) );
> >     myCaster->Update();
> >
> >     char s[100];
> >     sprintf(s,"level%d.pic",i);
> >     Pic2itk::saveImage<TInputImage2>(s,myCaster->GetOutput());
> >   }
> >
> >
> > just the image on the coarsest level is OK! The others are corrupted.
> > This seems due to CastImageFilter. If declaring a cast-filter
> > inside the for-loop, everything is OK!
> >
> >   myPyramid->SetNumberOfLevels(noLevels);
> >   myPyramid->SetInput(myCaster2->GetOutput() );
> >   myPyramid->UpdateLargestPossibleRegion();
> >
> >   for (int i=0 ; i<noLevels ; i++)
> >   {
> >     CastFilterType::Pointer myCaster = CastFilterType::New();
> >     myCaster->SetInput( myPyramid->GetOutput(i) );
> >     myCaster->Update();
> >
> >     char s[100];
> >     sprintf(s,"level%d.pic",i);
> >     Pic2itk::saveImage<TInputImage2>(s,myCaster->GetOutput());
> >   }
> >
> >
> > It seems, that the CastImageFilter doesn't work if SetInput is
> > called more than one time. Is this a bug or did I made something
> > wrong?
> >
> >
> > Mark
> > _______________________________________________
> > Insight-users mailing list
> > Insight-users@public.kitware.com
> > http://public.kitware.com/mailman/listinfo/insight-users
> >

-- 
Mark Hastenteufel
Deutsches Krebsforschungszentrum         (German Cancer Research Center)
Div. Medical and Biological Informatics H0100    Tel: (+49) 6221-42 2353
Im Neuenheimer Feld 280                          Fax: (+49) 6221-42 2345
D-69120 Heidelberg              e-mail            M.Hastenteufel@DKFZ.de
Germany                         http://www.dkfz.de/mbi/people/markh.html