Median Filtering of an Image

Synopsis

Apply median filtering on an image.

Results

Input image

Output image

Code

Python

#!/usr/bin/env python

import itk
import argparse

parser = argparse.ArgumentParser(description="Median Filtering Of An Image.")
parser.add_argument("input_image")
parser.add_argument("output_image")
parser.add_argument("radius", type=int)
args = parser.parse_args()

PixelType = itk.UC
Dimension = 2

ImageType = itk.Image[PixelType, Dimension]

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

medianFilter = itk.MedianImageFilter[ImageType, ImageType].New()
medianFilter.SetInput(reader.GetOutput())
medianFilter.SetRadius(args.radius)

writer = itk.ImageFileWriter[ImageType].New()
writer.SetFileName(args.output_image)
writer.SetInput(medianFilter.GetOutput())

writer.Update()

C++

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

int
main(int argc, char * argv[])
{
  if (argc != 4)
  {
    std::cerr << "Usage: " << std::endl;
    std::cerr << argv[0] << " <InputImageFile> <OutputImageFile> <radius>" << std::endl;
    return EXIT_FAILURE;
  }

  constexpr unsigned int Dimension = 2;

  const char * inputFileName = argv[1];
  const char * outputFileName = argv[2];
  const int    radiusValue = std::stoi(argv[3]);

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

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

  using FilterType = itk::MedianImageFilter<ImageType, ImageType>;
  FilterType::Pointer medianFilter = FilterType::New();

  FilterType::InputSizeType radius;
  radius.Fill(radiusValue);

  medianFilter->SetRadius(radius);
  medianFilter->SetInput(reader->GetOutput());

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

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

  return EXIT_SUCCESS;
}

Classes demonstrated

template<typename TInputImage, typename TOutputImage>
class MedianImageFilter : public itk::BoxImageFilter<TInputImage, TOutputImage>

Applies a median filter to an image.

Computes an image where a given pixel is the median value of the the pixels in a neighborhood about the corresponding input pixel.

A median filter is one of the family of nonlinear filters. It is used to smooth an image without being biased by outliers or shot noise.

This filter requires that the input pixel type provides an operator<() (LessThan Comparable).

See

Image

See

Neighborhood

See

NeighborhoodOperator

See

NeighborhoodIterator

ITK Sphinx Examples:

• All ITK Sphinx Examples

• Median Filter Of An Image

• Median Filter Of An RGB Image

See itk::MedianImageFilter for additional documentation.