[Insight-developers] compilation error of using DiscreteGaussianImageFilter with vector images

[Tom Vercauteren]

Hi Gang Song,

This is definitely a bug. Could you file a bug report? Submitting a
patch to gerrit would be even better.

A quick and dirty test shows that replacing
  // This filter can only operate on data types that are signed.
  if ( !NumericTraits< OutputPixelType >::is_signed )
by
  // This filter can only operate on data types that are signed.
  if ( !NumericTraits< typename NumericTraits< OutputPixelType
>::ValueType >::is_signed )
in itkNeighborhoodOperatorImageFilter.txx and replacing
  itkConceptMacro( OutputHasNumericTraitsCheck,
                   ( Concept::HasNumericTraits< OutputPixelType > ) );
by
  itkConceptMacro( OutputHasNumericTraitsCheck,
                   ( Concept::HasNumericTraits< typename
NumericTraits< OutputPixelType >::ValueType > ) );
seems to work ok.

A more elegant patch should thus be relatively easy to make by
changing at the right places
  OutputPixelType
by
  OutputPixelValueType
where you have
  typedef typename NumericTraits< OutputPixelType >::ValueType
OutputPixelValueType;

You may want to look at itk::RecursiveSeparableImageFilter and
itk::RecursiveGaussianImageFilter that already support vector images.

As a side note, it seems strange that Concept::HasNumericTraits<
itk::Vector<float,2> > chokes at compile time. Indeed itk::Vector have
numeric traits (look at itkNumericTraitsVectorPixel.h ) but the
concept check requires more functions to be defined (e.g. IsPositive).
I'll file a bug report about this particular point.

Tom

On Wed, Nov 17, 2010 at 22:58, gang song <songgang97 at gmail.com> wrote:
> Hi,
> I tried to use DiscreteGaussianImageFilter to smooth a vector image and got
> compilation error like:
> /ITK/InsightToolkit-3.20.0/Code/BasicFilters/itkNeighborhoodOperatorImageFilter.txx:95:
> error: ‘is_signed’ is not a member of ‘itk::NumericTraits<itk::Vector<float,
> 3u> >’
> NeighborhoodOperatorImageFilter is used in
> template< class TInputImage, class TOutputImage >
> void DiscreteGaussianImageFilter<TInputImage, TOutputImage>::GenerateData()
> {}
> Any suggestions about how to deal with this? This seems a general problem
> for vector image types with NeighborhoodOperatorImageFilter.
>
> Thanks
> -Gang
>
>
>
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