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Iterate Line Through Image

Synopsis

Iterate over a line through an image.

Results

Output In VTK Window

Code

C++

#include "itkImage.h"
#include "itkRGBPixel.h"
#include "itkImageFileReader.h"
#include "itkImageRegionIterator.h"
#include "itkLineIterator.h"

#include "itksys/SystemTools.hxx"

#ifdef ENABLE_QUICKVIEW
#  include "QuickView.h"
#endif

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

static void
CreateImage(ImageType::Pointer image);

int
main(int argc, char * argv[])
{
  auto        image = ImageType::New();
  std::string inputFilename;
  if (argc < 2)
  {
    CreateImage(image);
    inputFilename = "Synthetic";
  }
  else
  {
    image = itk::ReadImage<ImageType>(argv[1]);
    inputFilename = argv[1];
  }

  PixelType pixel;
  pixel.SetRed(255);
  pixel.SetGreen(127);
  pixel.SetBlue(50);

  ImageType::RegionType region = image->GetLargestPossibleRegion();
  ImageType::IndexType  corner1 = region.GetIndex();
  ImageType::IndexType  corner2;

  corner2[0] = corner1[0] + region.GetSize()[0] - 1;
  corner2[1] = corner1[1] + region.GetSize()[1] - 1;

  itk::LineIterator<ImageType> it1(image, corner1, corner2);
  it1.GoToBegin();
  while (!it1.IsAtEnd())
  {

    it1.Set(pixel);
    ++it1;
  }

#ifdef ENABLE_QUICKVIEW
  QuickView viewer;
  if (argc > 1)
  {
    viewer.AddImage<ImageType>(image, true, itksys::SystemTools::GetFilenameName(argv[1]));
  }
  else
  {
    viewer.AddImage<ImageType>(image, true, "Synthetic");
  }
  viewer.Visualize();
#endif
  return EXIT_SUCCESS;
}

void
CreateImage(ImageType::Pointer image)
{
  ImageType::SizeType regionSize;
  regionSize.Fill(100);

  ImageType::IndexType regionIndex;
  regionIndex.Fill(0);

  ImageType::RegionType region;
  region.SetSize(regionSize);
  region.SetIndex(regionIndex);

  PixelType pixel;
  pixel.SetRed(0);
  pixel.SetGreen(127);
  pixel.SetBlue(200);

  image->SetRegions(region);
  image->Allocate();
  image->FillBuffer(pixel);
}

Classes demonstrated

template<typename TImage>
class LineIterator : public itk::LineConstIterator<TImage>

An iterator that walks a Bresenham line through an ND image with write access to pixels.

LineIterator is an iterator that walks a Bresenham line through an image. The iterator is constructed similar to other image iterators, except instead of specifying a region to traverse, you specify two indices. The interval specified by the two indices is closed. So, a line iterator specified with the same start and end index will visit exactly one pixel.

LineConstIterator<ImageType> it(image, I1, I2);
while (!it.IsAtEnd())
{
   // visits at least 1 pixel
}

Author

Benjamin King, Experimentelle Radiologie, Medizinische Hochschule Hannover.

See

LineConstIterator

ITK Sphinx Examples:

• All ITK Sphinx Examples

• Iterate Line Through Image

See itk::LineIterator for additional documentation.