Threshold An Image Using Binary Thresholding

Synopsis

Binarize an input image by thresholding.

Results

Input image

Input image

Output image

Output image

Code

C++

#include "itkImageFileReader.h"
#include "itkImageFileWriter.h"
#include "itkImage.h"
#include "itkBinaryThresholdImageFilter.h"

int
main(int argc, char * argv[])
{
  if (argc < 7)
  {
    std::cerr << "Usage: " << std::endl;
    std::cerr << argv[0] << std::endl;
    std::cerr << " <InputImage> <OutputImage> <LowerThreshold>";
    std::cerr << " <UpperThreshold> <OutsideValue> <InsideValue>" << std::endl;
    return EXIT_FAILURE;
  }

  constexpr unsigned int Dimension = 2;
  using PixelType = unsigned char;

  const char * InputImage = argv[1];
  const char * OutputImage = argv[2];

  const auto LowerThreshold = static_cast<PixelType>(atoi(argv[3]));
  const auto UpperThreshold = static_cast<PixelType>(atoi(argv[4]));
  const auto OutsideValue = static_cast<PixelType>(atoi(argv[5]));
  const auto InsideValue = static_cast<PixelType>(atoi(argv[6]));

  using ImageType = itk::Image<PixelType, Dimension>;

  using ReaderType = itk::ImageFileReader<ImageType>;
  ReaderType::Pointer reader = ReaderType::New();
  reader->SetFileName(InputImage);

  using FilterType = itk::BinaryThresholdImageFilter<ImageType, ImageType>;
  FilterType::Pointer filter = FilterType::New();
  filter->SetInput(reader->GetOutput());
  filter->SetLowerThreshold(LowerThreshold);
  filter->SetUpperThreshold(UpperThreshold);
  filter->SetOutsideValue(OutsideValue);
  filter->SetInsideValue(InsideValue);

  using WriterType = itk::ImageFileWriter<ImageType>;
  WriterType::Pointer writer = WriterType::New();
  writer->SetFileName(OutputImage);
  writer->SetInput(filter->GetOutput());

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

  return EXIT_SUCCESS;
}

Python

#!/usr/bin/env python
import itk

if len(sys.argv) != 7:
    print("Usage: " + sys.argv[0] + " <inputImage> <outputImage> "
          "<lowerThreshold> <upperThreshold> <outsideValue> <insideValue>")
    sys.exit(1)

inputImage = sys.argv[1]
outputImage = sys.argv[2]
lowerThreshold = int(sys.argv[3])
upperThreshold = int(sys.argv[4])
outsideValue = int(sys.argv[5])
insideValue = int(sys.argv[6])

PixelType = itk.UC
Dimension = 2

ImageType = itk.Image[PixelType, Dimension]

reader = itk.ImageFileReader[ImageType].New()
reader.SetFileName(inputImage)

thresholdFilter = itk.BinaryThresholdImageFilter[ImageType, ImageType].New()
thresholdFilter.SetInput(reader.GetOutput())

thresholdFilter.SetLowerThreshold(lowerThreshold)
thresholdFilter.SetUpperThreshold(upperThreshold)
thresholdFilter.SetOutsideValue(outsideValue)
thresholdFilter.SetInsideValue(insideValue)

writer = itk.ImageFileWriter[ImageType].New()
writer.SetFileName(outputImage)
writer.SetInput(thresholdFilter.GetOutput())

writer.Update()

Classes demonstrated