ITK/Examples/ImageProcessing/UnaryFunctorImageFilter

Apply a custom function to every pixel in an image. In this example, we rotate every vector in a 2D VectorImage by 90 degrees.

UnaryFunctorImageFilter.cxx

<source lang="cpp">

1. include "itkVectorImage.h"
2. include "itkVector.h"
3. include "itkVariableLengthVector.h"
4. include "itkRigid2DTransform.h"
5. include "itkUnaryFunctorImageFilter.h"
6. include "vnl/vnl_math.h"

template< class TInput, class TOutput> class RotateVectors { public:

 RotateVectors() {};
 ~RotateVectors() {};
 bool operator!=( const RotateVectors & ) const
   {
   return false;
   }
 bool operator==( const RotateVectors & other ) const
   {
   return !(*this != other);
   }
 inline TOutput operator()( const TInput & A ) const
   {
     typedef itk::Vector<double, 2> VectorType;
     VectorType v;
     v[0] = A[0];
     v[1] = A[1];
           
     typedef itk::Rigid2DTransform< float > TransformType;

     TransformType::Pointer transform = TransformType::New();
     transform->SetAngle(vnl_math::pi/2.0);

     VectorType outputV = transform->TransformVector(v);
     TOutput transformedVector;
     transformedVector.SetSize(2);
     transformedVector[0] = outputV[0];
     transformedVector[1] = outputV[1];

     return transformedVector;
   }

};

int main(int, char *[]) {

 typedef itk::VectorImage<float, 2>  ImageType;

 ImageType::RegionType region;
 ImageType::IndexType start;
 start[0] = 0;
 start[1] = 0;

 ImageType::SizeType size;
 size[0] = 2;
 size[1] = 3;

 region.SetSize(size);
 region.SetIndex(start);

 ImageType::Pointer image = ImageType::New();
 image->SetRegions(region);
 image->SetVectorLength(2);
 image->Allocate();

 ImageType::IndexType pixelIndex;
 pixelIndex[0] = 1;
 pixelIndex[1] = 1;

 typedef itk::VariableLengthVector<float> VectorType;
 VectorType v;
 v.SetSize(2);
 v[0] = 1;
 v[1] = 0;
 
 image->SetPixel(pixelIndex, v);
 
 typedef itk::UnaryFunctorImageFilter<ImageType,ImageType,
                                 RotateVectors<
   ImageType::PixelType,
   ImageType::PixelType> > FilterType;

 FilterType::Pointer filter = FilterType::New();
 filter->SetInput(image);
 filter->Update();

 ImageType::PixelType inputPixelValue = image->GetPixel(pixelIndex);
 ImageType::PixelType outputPixelValue = filter->GetOutput()->GetPixel(pixelIndex);

 std::cout << "pixel (1,1) was = " << inputPixelValue << std::endl;
 std::cout << "pixel (1,1) now = " << outputPixelValue << std::endl;

 return EXIT_SUCCESS;

} </source>

CMakeLists.txt

<source lang="cmake"> cmake_minimum_required(VERSION 2.6)

PROJECT(UnaryFunctorImageFilter)

FIND_PACKAGE(ITK REQUIRED) INCLUDE(${ITK_USE_FILE})

ADD_EXECUTABLE(UnaryFunctorImageFilter UnaryFunctorImageFilter.cxx) TARGET_LINK_LIBRARIES(UnaryFunctorImageFilter ITKIO ITKBasicFilters ITKCommon )

</source>