Apply a Filter Only to a Specified Image Region#

Synopsis#

To apply a filter to only operate on a specified ImageRegion.

Results#

Output:

Created random image.
Computed derivative.

Code#

C++#

#include "itkImage.h"
#include "itkRandomImageSource.h"
#include "itkDerivativeImageFilter.h"

int
main()
{
  using ImageType = itk::Image<float, 2>;

  itk::Size<2> smallSize;
  smallSize.Fill(10);

  itk::Index<2> index;
  index.Fill(0);

  itk::ImageRegion<2> region(index, smallSize);

  itk::Size<2> bigSize;
  bigSize.Fill(10000);

  itk::RandomImageSource<ImageType>::Pointer randomImageSource = itk::RandomImageSource<ImageType>::New();
  randomImageSource->SetNumberOfWorkUnits(1); // to produce non-random results
  randomImageSource->SetSize(bigSize);
  randomImageSource->GetOutput()->SetRequestedRegion(smallSize);
  randomImageSource->Update();

  std::cout << "Created random image." << std::endl;

  using DerivativeImageFilterType = itk::DerivativeImageFilter<ImageType, ImageType>;
  auto derivativeFilter = DerivativeImageFilterType::New();
  derivativeFilter->SetInput(randomImageSource->GetOutput());
  derivativeFilter->SetDirection(0); // "x" axis
  derivativeFilter->GetOutput()->SetRequestedRegion(smallSize);
  derivativeFilter->Update();

  std::cout << "Computed derivative." << std::endl;

  return EXIT_SUCCESS;
}

Classes demonstrated#

template<typename TInputImage, typename TOutputImage> class DerivativeImageFilter : public itk::ImageToImageFilter<TInputImage, TOutputImage>

Computes the directional derivative of an image. The directional derivative at each pixel location is computed by convolution with a derivative operator of user-specified order.

SetOrder specifies the order of the derivative.

SetDirection specifies the direction of the derivative with respect to the coordinate axes of the image.

See

Image

See

Neighborhood

See

NeighborhoodOperator

See

NeighborhoodIterator

ITK Sphinx Examples: