[Insight-users] Bug in itkShrinkImageFilter

[Koen Van Leemput]

Hi,

I think there is a bug in=20
itkShrinkImageFilter::GenerateInputRequestedRegion(). More specifically, =
the=20
size of the inputRequestedRegion is not calculated properly.

Here is some code reproducing the error:

  typedef itk::ImageRegion<1>        RegionType;
  typedef itk::Image<float, 1>          ImageType;
  typedef itk::ShrinkImageFilter<ImageType, ImageType>  ShrinkerType;

  RegionType::IndexType    index =3D {5};
  RegionType::SizeType     size =3D {10};
  RegionType region(index, size);

  ImageType::Pointer  image =3D ImageType::New();
  image->SetRegions( region );
  image->Allocate();

  ShrinkerType::Pointer   shrinker =3D ShrinkerType::New();
  shrinker->SetInput( image );
  shrinker->SetShrinkFactors( 2 );
  try
    {
      shrinker->Update();
    }
  catch( itk::ExceptionObject & err )
    {
      std::cout << "Caught an exception: " << std::endl;
      std::cout << err << std::endl;
      std::cout << image->GetLargestPossibleRegion() << std::endl;
      std::cout << image->GetRequestedRegion() << std::endl;
    }


In itkShrinkImageFilter::GenerateInputRequestedRegion(), the calculation =
of=20
the size is    =20

  inputRequestedRegionSize[i]
      =3D outputRequestedRegionSize[i] * m_ShrinkFactors[i];

but should be

  inputRequestedRegionSize[i]
      =3D outputRequestedRegionSize[i] * m_ShrinkFactors[i]=20
         - m_ShrinkFactors[i] + 1;

Cheers,

Koen



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Koen Van Leemput, Ph.D.                email : koen.vanleemput@hus.fi=20
Department of Radiology                  phone: +358 9 471 71331       =20
Helsinki University Central Hospital   mobile: +358 9 471 62300       =20
P.O. Box 340                                  fax:      +358 9 471 71342 =
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FIN-00029 HUS                                                            =
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FINLAND                                                                  =
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