[Insight-users] [Community] Resampling: defining the output size at 'runtime' (Update-time) relative to the input size
Vaaksiainen
vaaksiainen at gmail.com
Thu Oct 17 02:55:18 EDT 2013
Thanks again for your comments Matt! As you see, I already 'graft' :)
Based on your comments, I modified my code which got me started. Then using
debugger further, I figured out I'd better implementing also
VerifyInputInformation() and GenerateInputRequestedRegion(). In outcome, I
now do have a working copy. So simple I'll just share it here. Not sure
what happens when region-index is nonzero but for time being its ok.
Best,
-Vaaksiainen
***
template < class TInputImage, class TOutputImage >
class ResizeImageFilter :
public itk::ImageToImageFilter<TInputImage, TOutputImage>
{
public:
typedef ResizeImageFilter Self;
typedef itk::ImageToImageFilter<TInputImage,TOutputImage> Superclass;
typedef itk::SmartPointer<Self> Pointer;
typedef typename TInputImage::SpacingType SpacingType;
typedef typename TOutputImage::SizeType SizeType;
itkNewMacro( Self );
itkTypeMacro( ResizeImageFilter, itk::ImageToImageFilter );
itkSetMacro( Scale, SpacingType );
itkSetMacro( Size, SizeType );
protected:
ResizeImageFilter()
{
m_Size.Fill( 0 );
m_Scale.Fill( 1 );
}
~ResizeImageFilter(){}
void VerifyInputInformation() {}
void GenerateData();
void GenerateOutputInformation();
void GenerateInputRequestedRegion();
private:
ResizeImageFilter & operator=(const ResizeImageFilter &rhs);
ResizeImageFilter( const ResizeImageFilter &rhs);
SpacingType m_Scale;
SizeType m_Size;
SpacingType m_SpacingActual;
SizeType m_SizeActual;
};
template < class TInputImage, class TOutputImage >
void ResizeImageFilter<TInputImage,TOutputImage>
::GenerateData()
{
typedef itk::ResampleImageFilter<TInputImage,TOutputImage,float>
ResamplerType;
ResamplerType::Pointer resampler = ResamplerType::New();
resampler->SetOutputSpacing( m_SpacingActual );
resampler->SetSize( m_SizeActual );
resampler->SetInput( this->GetInput() );
resampler->GraftOutput( this->GetOutput() );
resampler->Update();
this->GraftOutput( resampler->GetOutput() );
}
template < class TInputImage, class TOutputImage >
void ResizeImageFilter<TInputImage,TOutputImage>
::GenerateInputRequestedRegion()
{
this->itk::ProcessObject::GenerateInputRequestedRegion();
}
template < class TInputImage, class TOutputImage >
void ResizeImageFilter<TInputImage,TOutputImage>
::GenerateOutputInformation()
{
const TInputImage * p = this->GetInput();
if( p )
{
const unsigned int N = TInputImage::ImageDimension;
double decimation[N];
m_SizeActual = p->GetRequestedRegion().GetSize();
m_SpacingActual = p->GetSpacing();
for ( unsigned int n = 0; n < N; ++n )
{
if ( m_Size[n] == 0 )
decimation[n] = m_Scale[n];
else
decimation[n] = (double)m_Size[n]/(double)m_SizeActual[n];
}
for ( unsigned int n = 0; n < N; ++n )
{
m_SpacingActual[n] /= decimation[n];
m_SizeActual[n] = (unsigned int)( (double)m_SizeActual[n] *
decimation[n] );
if ( m_SpacingActual[n] <= 0.0 || m_SizeActual[n] == 0 )
itkExceptionMacro("spacing[n] <= 0 || size[n] == 0" );
}
TOutputImage * pOut = this->GetOutput();
if ( pOut )
{
pOut->CopyInformation( p );
pOut->SetSpacing( m_SpacingActual );
typename TOutputImage::RegionType region =
pOut->GetRequestedRegion();
region.SetSize( m_SizeActual );
pOut->SetLargestPossibleRegion( region );
pOut->SetSpacing( m_SpacingActual );
}
}
}
***
2013/10/16 Matt McCormick <matt.mccormick at kitware.com>
> Hi Vaaksiainen,
>
> The filter should implement a GenerateOutputInformation() [1] method
> that does the size calculation there and assigns it to the output
> ImageRegion's.
>
> Hope this helps,
> Matt
>
> [1]
> http://www.itk.org/Doxygen/html/classitk_1_1ProcessObject.html#abe61fb6b7de8c443e7af1561bd722736
>
> On Wed, Oct 16, 2013 at 2:42 PM, Vaaksiainen <vaaksiainen at gmail.com>
> wrote:
> > Thanks for your quick reply, really appreciate.
> >
> > I could well be using itk::ScaleTransform but I use simply resampling
> over
> > hand written spacing. I think my problem is in fact in pipelining:
> >
> > void ResampleImageFilterEx<TInputImage,TOutputImage>::GenerateData()
> > {
> > //....
> > typename TInputImage::RegionType roi =
> > this->GetOutput()->GetRequestedRegion();
> > typename TInputImage::SpacingType spacing =
> > this->GetInput()->GetSpacing();
> > typename TInputImage::SizeType size = roi.GetSize();
> >
> > for ( unsigned int i = 0; i < TInputImage::ImageDimension; ++i)
> > {
> > spacing[i] /= m_Decimation;
> > size[i] = (unsigned int)( (double)size[i] * m_Decimation );
> > }
> > itk::ResampleImageFilter<TInputImage,TOutputImage>::Pointer
> resampler =
> > itk::ResampleImageFilter<TInputImage,TOutputImage>::New();
> >
> > resampler->SetOutputSpacing( inputSpacing );
> > resampler->SetSize( inputSize );
> > resampler->SetInput( this->GetInput() );
> >
> > resampler->GraftOutput( this->GetOutput() );
> > resampler->Update();
> > resampler->GraftOutput( pyrup->GetOutput() );
> > }
> >
> > but if m_Decimation (or scale parameter) is given as parameter and input
> yet
> > unknown, I can't get regions propagating correctly. Because eventually I
> > want to call Update only for the tail filter.
> >
> > Best,
> > -Vaaksiainen
> >
> >
> >
> > 2013/10/16 Mike Chinander <chinander at gmail.com>
> >>
> >> Check out the following example:
> >> http://www.itk.org/Wiki/ITK/Examples/ImageProcessing/ScaleTransform
> >>
> >>
> >> On Wed, Oct 16, 2013 at 9:10 AM, Vaaksiainen <vaaksiainen at gmail.com>
> >> wrote:
> >>>
> >>> Hi folks,
> >>>
> >>> itk::ResampleImageFilter requires size being set before Update() so far
> >>> that I've understood it.
> >>>
> >>> That being said, I'd wish to implement resize image filter (derivative
> >>> for before mentioned) which samples the image based on scaling
> parameter
> >>> relative to its input size e.g.
> >>>
> >>> newWidth = scaling * oldWidth
> >>>
> >>> which I figure out at GenerateData() and yet, I'd wish to be able to
> put
> >>> this filter in the pipeline not knowing the size of the input image,
> e.g.
> >>>
> >>> Reader -> Filter#1 -> ResampleImageFilterEx -> Filter#2 -> Writer
> >>>
> >>> How PropagateRequestedRegion() works and how its implemented in
> >>> itk::ResampleImageFilter I'm not sure if I can do this at all.
> >>>
> >>> Please, any advice?
> >>>
> >>> Best,
> >>> -Vaaksiainen
> >>>
> >>>
> >>>
> >>>
> >>>
> >>> _____________________________________
> >>> Powered by www.kitware.com
> >>>
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> >>
> >>
> >> _____________________________________
> >> Powered by www.kitware.com
> >>
> >> Visit other Kitware open-source projects at
> >> http://www.kitware.com/opensource/opensource.html
> >>
> >> Kitware offers ITK Training Courses, for more information visit:
> >> http://www.kitware.com/products/protraining.php
> >>
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> >>
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> >>
> >
> >
> > _____________________________________
> > Powered by www.kitware.com
> >
> > Visit other Kitware open-source projects at
> > http://www.kitware.com/opensource/opensource.html
> >
> > Kitware offers ITK Training Courses, for more information visit:
> > http://www.kitware.com/products/protraining.php
> >
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> > http://www.itk.org/Wiki/ITK_FAQ
> >
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