[Insight-users] Absolute Value Image

[Glen Lehmann]

Great! Thanks, Luis. 

I figured I'd end up doing this but I just wanted to be certain I wasn't 
overlooking anything.

Thanks again for putting one together for me.

Glen

Luis Ibanez wrote:

> Hi Glen,
>
> Bad  news:  There is not an absolute value filter in ITK
>
> Good news:  You can write one in ten minutes.
>             (7 minutes if you have good coffee at hand)
>
> Even better news: One is attached.
>
>
> --------------------------------------------------------
>
> Simply take any of the filters deriving from the UnaryFunctorFilter
> and replace the Functor with the "Abs()" function.
> Take for example the "Sin" image filter
>
>     Insight/Code/BasicFilters/itkSinImageFilter.h
>
>
> This will look like:
>
>
> namespace Function {
>
> template< class TInput, class TOutput>
> class Abs
> {
> public:
>   Abs() {}
>   ~Abs() {}
>   inline TOutput operator()( const TInput & A )
>   { return (TOutput)( ( A > 0 ) ? A : -A ); }
> };
> }
>
> Then use this functor for instantiating the filter.
> This is shown in the attached file. Note that there
> is only a header file, and that's all what is needed.
> Here is where Generic Programming pays off.   :-)
>
>
> ---------------------------------------------------------------------
>
>
> Given that Abs is such a simple operation you may want
> to use ImageAdaptors instead of ImageFilters.
>
> You will find details on who to write functional
> ImageAdaptors in the SoftwareGuide
>
>    http://www . itk . org/ItkSoftwareGuide . pdf
>
> Please look at the ImageAdaptors chapter,
> Chapter 12, pdf-page 522, paper-page 548.
>
> Functional adaptors are described in section 12.4
> The example of this section is available in
>
>   Insight/Examples/DataRepresentation/Image/ImageAdaptor4.cxx
>
>
> Please let us know if you run into any problem.
>
>
>
>    Thanks
>
>
>
>      Luis
>
>
>
>
> ----------------------
> Glen Lehmann wrote:
>
>> Hello,
>>
>> Here's an easy one;  Is there an ITK class to find that absolute 
>> value of an image?
>>
>> i.e. in vtk I'd use vtkImageMathematics->SetOperationToAbsoluteValue.
>>
>> I didn't have any luck in the archives.
>>
>> Thanks,
>> Glen
>>
> \
>
>------------------------------------------------------------------------
>
>/*=========================================================================
>
>  Program:   Insight Segmentation & Registration Toolkit
>  Module:    $RCSfile: itkAbsImageFilter.h,v $
>  Language:  C++
>  Date:      $Date: 2003/09/10 14:28:56 $
>  Version:   $Revision: 1.16 $
>
>  Copyright (c) Insight Software Consortium. All rights reserved.
>  See ITKCopyright.txt or http://www . itk . org/HTML/Copyright . htm for details.
>
>     This software is distributed WITHOUT ANY WARRANTY; without even 
>     the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR 
>     PURPOSE.  See the above copyright notices for more information.
>
>=========================================================================*/
>#ifndef __itkAbsImageFilter_h
>#define __itkAbsImageFilter_h
>
>#include "itkUnaryFunctorImageFilter.h"
>#include "vnl/vnl_math.h"
>
>namespace itk
>{
>  
>/** \class AbsImageFilter
> * \brief Computes the ABS(x) pixel-wise
> * 
> * \ingroup IntensityImageFilters  Multithreaded
> */
>namespace Function {  
>  
>template< class TInput, class TOutput>
>class Abs
>{
>public:
>  Abs() {}
>  ~Abs() {}
>  inline TOutput operator()( const TInput & A )
>  { return (TOutput)( ( A > 0 ) ? A : -A ); }
>}; 
>}
>
>template <class TInputImage, class TOutputImage>
>class ITK_EXPORT AbsImageFilter :
>    public
>UnaryFunctorImageFilter<TInputImage,TOutputImage, 
>                        Function::Abs< 
>  typename TInputImage::PixelType, 
>  typename TOutputImage::PixelType>   >
>{
>public:
>  /** Standard class typedefs. */
>  typedef AbsImageFilter  Self;
>  typedef UnaryFunctorImageFilter<TInputImage,TOutputImage, 
>                                  Function::Abs< typename TInputImage::PixelType, 
>                                                 typename TOutputImage::PixelType> >  Superclass;
>  typedef SmartPointer<Self>   Pointer;
>  typedef SmartPointer<const Self>  ConstPointer;
>
>  /** Method for creation through the object factory. */
>  itkNewMacro(Self);
>  
>protected:
>  AbsImageFilter() {}
>  virtual ~AbsImageFilter() {}
>
>private:
>  AbsImageFilter(const Self&); //purposely not implemented
>  void operator=(const Self&); //purposely not implemented
>
>};
>
>} // end namespace itk
>
>
>#endif
>  
>