Extract Component of Vector Image

Synopsis

Extract a component/channel of a vector image.

Results

Code

C++

#include "itkVectorImage.h"
#include "itkImageRegionIterator.h"
#include "itkMinimumMaximumImageCalculator.h"
#include "itkVectorIndexSelectionCastImageFilter.h"

using VectorImageType = itk::VectorImage<float, 2>;
using ScalarImageType = itk::Image<float, 2>;

static void
CreateImage(VectorImageType::Pointer image);

int
main(int, char *[])
{
  VectorImageType::Pointer image = VectorImageType::New();
  CreateImage(image);

  using IndexSelectionType = itk::VectorIndexSelectionCastImageFilter<VectorImageType, ScalarImageType>;
  IndexSelectionType::Pointer indexSelectionFilter = IndexSelectionType::New();
  indexSelectionFilter->SetIndex(0);
  indexSelectionFilter->SetInput(image);

  using ImageCalculatorFilterType = itk::MinimumMaximumImageCalculator<ScalarImageType>;
  ImageCalculatorFilterType::Pointer imageCalculatorFilter = ImageCalculatorFilterType::New();
  imageCalculatorFilter->SetImage(indexSelectionFilter->GetOutput());
  imageCalculatorFilter->Compute();

  return EXIT_SUCCESS;
}

void
CreateImage(VectorImageType::Pointer image)
{
  VectorImageType::IndexType start;
  start.Fill(0);

  VectorImageType::SizeType size;
  size.Fill(2);

  VectorImageType::RegionType region(start, size);

  image->SetRegions(region);
  image->SetNumberOfComponentsPerPixel(3);
  image->Allocate();

  using VariableVectorType = itk::VariableLengthVector<double>;
  VariableVectorType variableLengthVector;
  variableLengthVector.SetSize(3);
  variableLengthVector[0] = 1.1;
  variableLengthVector[1] = 2.2;
  variableLengthVector[2] = 3.3;

  image->FillBuffer(variableLengthVector);
}

Classes demonstrated

template<typename TInputImage, typename TOutputImage>
class VectorIndexSelectionCastImageFilter : public itk::UnaryFunctorImageFilter<TInputImage, TOutputImage, Functor::VectorIndexSelectionCast<TInputImage::PixelType, TOutputImage::PixelType>>

Extracts the selected index of the vector that is the input pixel type.

This filter is templated over the input image type and output image type.

The filter expect the input image pixel type to be a vector and the output image pixel type to be a scalar. The only requirement on the type used for representing the vector is that it must provide an operator[].

See

ComposeImageFilter

ITK Sphinx Examples:

• All ITK Sphinx Examples

• Extract Component Of Vector Image

See itk::VectorIndexSelectionCastImageFilter for additional documentation.