Image Region Overlap¶

Synopsis¶

Determine the overlap of two regions

Results¶

Code¶

C++¶

#include <cstdlib>
#include <cstdio>

#include "itkRGBPixel.h"
#include "itkImageRegionIterator.h"
#include "itkImageFileWriter.h"


int
main(int argc, char * argv[])
{
  if (argc != 2)
  {
    std::cerr << "Usage: " << std::endl;
    std::cerr << argv[0] << std::endl;
    std::cerr << " <OutputFileName>" << std::endl;

    return EXIT_FAILURE;
  }
  const char * out_file_name = argv[1];

  constexpr unsigned int Dimension = 2;
  using RGBPixelType = itk::RGBPixel<unsigned char>;
  using RGBImageType = itk::Image<RGBPixelType, Dimension>;
  using RegionType = RGBImageType::RegionType;
  using IndexType = RGBImageType::IndexType;
  using SizeType = RGBImageType::SizeType;
  using IteratorType = itk::ImageRegionIterator<RGBImageType>;


  IndexType index;
  index[0] = 0;
  index[1] = 0;

  SizeType size;
  size[0] = 100;
  size[1] = 100;

  RegionType region;
  region.SetIndex(index);
  region.SetSize(size);

  IndexType indexA;
  indexA[0] = 9;
  indexA[1] = 9;

  SizeType sizeA;
  sizeA[0] = 50;
  sizeA[1] = 50;

  RegionType regionA;
  regionA.SetIndex(indexA);
  regionA.SetSize(sizeA);

  IndexType indexB;
  indexB[0] = 39;
  indexB[1] = 39;

  SizeType sizeB;
  sizeB[0] = 50;
  sizeB[1] = 50;

  RegionType regionB;
  regionB.SetIndex(indexB);
  regionB.SetSize(sizeB);

  // Region C is the intersection of A and B
  // padded by 10 pixels.
  RegionType regionC = regionA;
  regionC.Crop(regionB);
  regionC.PadByRadius(10);

  RGBPixelType pix_black;
  pix_black.Fill(0);

  RGBPixelType pix_red;
  pix_red.Fill(0);
  pix_red[0] = 255;

  RGBPixelType pix_green;
  pix_green.Fill(0);
  pix_green[1] = 255;

  RGBPixelType pix_blue;
  pix_blue.Fill(0);
  pix_blue[2] = 255;

  // A black canvas
  RGBImageType::Pointer image = RGBImageType::New();
  image->SetRegions(region);
  image->Allocate();
  image->FillBuffer(pix_black);

  // Paint region A red.
  IteratorType itA(image, regionA);
  itA.GoToBegin();
  while (!itA.IsAtEnd())
  {
    itA.Set(itA.Get() + pix_red);
    ++itA;
  }

  // Paint region B green.
  IteratorType itB(image, regionB);
  itB.GoToBegin();
  while (!itB.IsAtEnd())
  {
    itB.Set(itB.Get() + pix_green);
    ++itB;
  }

  // Paint region C blue.
  IteratorType itC(image, regionC);
  itC.GoToBegin();
  while (!itC.IsAtEnd())
  {
    itC.Set(itC.Get() + pix_blue);
    ++itC;
  }

  // Writer
  using FileWriterType = itk::ImageFileWriter<RGBImageType>;
  FileWriterType::Pointer writer = FileWriterType::New();
  writer->SetFileName(out_file_name);
  writer->SetInput(image);

  try
  {
    writer->Update();
  }
  catch (itk::ExceptionObject & error)
  {
    std::cerr << "Error: " << error << std::endl;
    return EXIT_FAILURE;
  }

  return EXIT_SUCCESS;
}

Classes demonstrated¶

template<unsigned int VImageDimension> class ImageRegion : public itk::Region

An image region represents a structured region of data.

ImageRegion is an class that represents some structured portion or piece of an Image. The ImageRegion is represented with an index and a size in each of the n-dimensions of the image. (The index is the corner of the image, the size is the lengths of the image in each of the topological directions.)

See

Region

See

Index

See

Size

See

MeshRegion

ITK Sphinx Examples: