Statistical Properties Of Labeled Regions

Synopsis

Get statistical properties of labeled regions in an image.

Results

image.png

image.png

Output:

Number of labels: 2

min: 255
max: 255
median: 0
mean: 255
sigma: 0
variance: 0
sum: 4080
count: 16
region: ImageRegion (0x7ffedfd04a28)
Dimension: 2
Index: [6, 6]
Size: [4, 4]

min: 0
max: 0
median: 0
mean: 0
sigma: 0
variance: 0
sum: 0
count: 384
region: ImageRegion (0x7ffedfd04a28)
Dimension: 2
Index: [0, 0]
Size: [20, 20]

Code

C++

#include "itkImage.h"
#include "itkImageFileWriter.h"
#include "itkImageRegionIterator.h"
#include "itkBinaryImageToLabelMapFilter.h"
#include "itkLabelMapToLabelImageFilter.h"
#include "itkLabelStatisticsImageFilter.h"

using ImageType = itk::Image<unsigned char, 2>;
static void
CreateImage(ImageType::Pointer image);

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

  using BinaryImageToLabelMapFilterType = itk::BinaryImageToLabelMapFilter<ImageType>;
  BinaryImageToLabelMapFilterType::Pointer binaryImageToLabelMapFilter = BinaryImageToLabelMapFilterType::New();
  binaryImageToLabelMapFilter->SetInput(image);
  binaryImageToLabelMapFilter->Update();

  using LabelMapToLabelImageFilterType =
    itk::LabelMapToLabelImageFilter<BinaryImageToLabelMapFilterType::OutputImageType, ImageType>;
  LabelMapToLabelImageFilterType::Pointer labelMapToLabelImageFilter = LabelMapToLabelImageFilterType::New();
  labelMapToLabelImageFilter->SetInput(binaryImageToLabelMapFilter->GetOutput());
  labelMapToLabelImageFilter->Update();

  using LabelStatisticsImageFilterType = itk::LabelStatisticsImageFilter<ImageType, ImageType>;
  LabelStatisticsImageFilterType::Pointer labelStatisticsImageFilter = LabelStatisticsImageFilterType::New();
  labelStatisticsImageFilter->SetLabelInput(labelMapToLabelImageFilter->GetOutput());
  labelStatisticsImageFilter->SetInput(image);
  labelStatisticsImageFilter->Update();

  std::cout << "Number of labels: " << labelStatisticsImageFilter->GetNumberOfLabels() << std::endl;
  std::cout << std::endl;

  using LabelPixelType = LabelStatisticsImageFilterType::LabelPixelType;

  for (auto vIt = labelStatisticsImageFilter->GetValidLabelValues().begin();
       vIt != labelStatisticsImageFilter->GetValidLabelValues().end();
       ++vIt)
  {
    if (labelStatisticsImageFilter->HasLabel(*vIt))
    {
      LabelPixelType labelValue = *vIt;
      std::cout << "min: " << labelStatisticsImageFilter->GetMinimum(labelValue) << std::endl;
      std::cout << "max: " << labelStatisticsImageFilter->GetMaximum(labelValue) << std::endl;
      std::cout << "median: " << labelStatisticsImageFilter->GetMedian(labelValue) << std::endl;
      std::cout << "mean: " << labelStatisticsImageFilter->GetMean(labelValue) << std::endl;
      std::cout << "sigma: " << labelStatisticsImageFilter->GetSigma(labelValue) << std::endl;
      std::cout << "variance: " << labelStatisticsImageFilter->GetVariance(labelValue) << std::endl;
      std::cout << "sum: " << labelStatisticsImageFilter->GetSum(labelValue) << std::endl;
      std::cout << "count: " << labelStatisticsImageFilter->GetCount(labelValue) << std::endl;
      // std::cout << "box: " << labelStatisticsImageFilter->GetBoundingBox( labelValue ) << std::endl; // can't output
      // a box
      std::cout << "region: " << labelStatisticsImageFilter->GetRegion(labelValue) << std::endl;
      std::cout << std::endl << std::endl;
    }
  }

  return EXIT_SUCCESS;
}

void
CreateImage(ImageType::Pointer image)
{
  // Create a black image with a white square
  ImageType::IndexType start;
  start.Fill(0);

  ImageType::SizeType size;
  size.Fill(20);

  ImageType::RegionType region;
  region.SetSize(size);
  region.SetIndex(start);
  image->SetRegions(region);
  image->Allocate();

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

  // Make a square
  while (!imageIterator.IsAtEnd())
  {
    if ((imageIterator.GetIndex()[0] > 5 && imageIterator.GetIndex()[0] < 10) &&
        (imageIterator.GetIndex()[1] > 5 && imageIterator.GetIndex()[1] < 10))
    {
      imageIterator.Set(255);
    }
    else
    {
      imageIterator.Set(0);
    }

    ++imageIterator;
  }

  using WriterType = itk::ImageFileWriter<ImageType>;
  WriterType::Pointer writer = WriterType::New();
  writer->SetFileName("image.png");
  writer->SetInput(image);
  writer->Update();
}

Classes demonstrated