Store Non-Pixel Data In Image#

Note

Wish List Still needs additional work to finish proper creation of example.

Synopsis#

Store non-pixel associated data in an image.

Results#

Note

Help Wanted Implementation of Results for sphinx examples containing this message. Reconfiguration of CMakeList.txt may be necessary. Write An Example <https://itk.org/ITKExamples/Documentation/Contribute/WriteANewExample.html>

Code#

C++#

#include <itkImage.h>
#include <itkMetaDataDictionary.h>
#include <itkMetaDataObject.h>
#include <itkImageRegionIterator.h>
#include <itkImageFileWriter.h>
#include <itkImageFileReader.h>

using ImageType = itk::Image<unsigned char, 2>;

static void
CreateImage(ImageType::Pointer image);

int
main()
{
  // Create an image
  auto image = ImageType::New();
  CreateImage(image);

  // Store some data in it
  itk::MetaDataDictionary dictionary;
  itk::EncapsulateMetaData<float>(dictionary, "ASimpleFloat", 1.2);
  image->SetMetaDataDictionary(dictionary);

  // View all of the data
  dictionary.Print(std::cout);

  // View the data individually
  auto itr = dictionary.Begin();

  while (itr != dictionary.End())
  {
    std::cout << "Key   = " << itr->first << std::endl;
    std::cout << "Value = ";
    itr->second->Print(std::cout);
    std::cout << std::endl;
    ++itr;
  }

  // Write the image (and the data) to a file
  using WriterType = itk::ImageFileWriter<ImageType>;
  auto writer = WriterType::New();
  writer->SetFileName("test.mhd");
  writer->SetInput(image);
  writer->Update();

  // Read the image (and data) from the file
  using ReaderType = itk::ImageFileReader<ImageType>;
  auto reader = ReaderType::New();
  reader->SetFileName("test.mhd");

  // Display the data
  std::cout << "Data read from file:" << std::endl;
  reader->GetMetaDataDictionary().Print(std::cout);

  return EXIT_SUCCESS;
}

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

  ImageType::SizeType size;
  size.Fill(10);

  ImageType::RegionType region;
  region.SetSize(size);
  region.SetIndex(start);

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

  itk::ImageRegionIterator<ImageType> imageIterator(image, image->GetLargestPossibleRegion());

  while (!imageIterator.IsAtEnd())
  {
    imageIterator.Set(20);
    ++imageIterator;
  }
}

Classes demonstrated#

class MetaDataDictionary

Provides a mechanism for storing a collection of arbitrary data types.

The

MetaDataDictionary, along with the MetaDataObject derived template classes, is designed to provide a mechanism for storing a collection of arbitrary data types. The main motivation for such a collection is to associate arbitrary data elements with itk DataObjects.
Author

Hans J. Johnson

The MetaDataDictionary implements shallow copying with copy on write behavior. When a copy of this class is created, the new copy will be shared with the old copy via C++11 shared pointers. When a non-constant operation is done, if the dictionary is not unique to this object, then a deep copy is performed. This make is very cheap to create multiple copies of the same dictionary if they are never modified.

ITK Sphinx Examples:

See itk::MetaDataDictionary for additional documentation.