ITK/Examples/Smoothing/RGBMedianImageFilter

This examples creates a subclass of RGBPixel that overrides the operator <= method. The operator compares luminances of pixels.

RGBMedianImageFilter.cxx

<source lang="cpp">

1. include "itkMedianImageFilter.h"

1. include "itkImage.h"
2. include "itkImageFileReader.h"
3. include "itkSubtractImageFilter.h"
4. include "itkRGBPixel.h"
5. include "itkCastImageFilter.h"

1. include "itksys/SystemTools.hxx"

1. include <sstream>

1. include "QuickView.h"

namespace itk { /** \class myRGBPixel

* \brief Extends RGBPixel with operator <=
*
* This class overrides the <= operator to use Luminance as a sorting value.
*/

template< typename TComponent = unsigned short > class myRGBPixel : public RGBPixel<TComponent> { public:

 typedef myRGBPixel           Self;
 typedef RGBPixel<TComponent> Superclass;
 using RGBPixel<TComponent>::operator=;

 bool operator<=(const Self & r) const
 {
   if (this->GetLuminance() <= r.GetLuminance())
     {
     return true;
     }
   else
     {
     return false;
     }
 }

}; }

int main(int argc, char * argv[]) {

 // Verify command line arguments
 if( argc < 2 )
   {
   std::cerr << "Usage: " << std::endl;
   std::cerr << argv[0] << " InputImageFile [radius]" << std::endl;
   return EXIT_FAILURE;
   }
 std::string inputFilename = argv[1];

 // Setup types
 typedef itk::myRGBPixel<unsigned char>                      PixelType;
 typedef itk::Image<PixelType, 2 >                           ImageType;
 typedef itk::RGBPixel<unsigned char>                        RGBPixelType;
 typedef itk::Image<RGBPixelType, 2 >                        RGBImageType;

 typedef itk::ImageFileReader<ImageType>                     ReaderType;
 typedef itk::MedianImageFilter<ImageType, ImageType >       FilterType;
 typedef itk::SubtractImageFilter<RGBImageType>              SubtractType;
 typedef itk::CastImageFilter<ImageType, RGBImageType>       CastType;

 // Create and setup a reader
 ReaderType::Pointer reader = ReaderType::New();
 reader->SetFileName( inputFilename );

 // Create and setup a median filter
 FilterType::Pointer medianFilter = FilterType::New();
 FilterType::InputSizeType radius;
 radius.Fill(2);
 if (argc > 2)
   {
   radius.Fill(atoi(argv[2]));
   }

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

 // Cast the custom myRBGPixel's to RGBPixel's
 CastType::Pointer castReader = CastType::New();
 castReader->SetInput(reader->GetOutput());

 CastType::Pointer castMedian = CastType::New();
 castMedian->SetInput(medianFilter->GetOutput());

 SubtractType::Pointer diff = SubtractType::New();
 diff->SetInput1(castMedian->GetOutput());
 diff->SetInput2(castReader->GetOutput());

 QuickView viewer;
 viewer.AddRGBImage(
   castReader->GetOutput(),
   true,
   itksys::SystemTools::GetFilenameName(inputFilename));  

 std::stringstream desc;
 desc << "MedianImageFilter, radius = " << radius;
 viewer.AddRGBImage(
   castMedian->GetOutput(),
   true,
   desc.str());  

 std::stringstream desc2;
 desc2 << "Original - Median";
 viewer.AddRGBImage(
   diff->GetOutput(),
   true,
   desc2.str());  

 viewer.Visualize();

 return EXIT_SUCCESS;

} </source>

CMakeLists.txt

<syntaxhighlight lang="cmake"> cmake_minimum_required(VERSION 3.9.5)

project(RGBMedianImageFilter)

find_package(ITK REQUIRED) include(${ITK_USE_FILE}) if (ITKVtkGlue_LOADED)

 find_package(VTK REQUIRED)
 include(${VTK_USE_FILE})

else()

 find_package(ItkVtkGlue REQUIRED)
 include(${ItkVtkGlue_USE_FILE})
 set(Glue ItkVtkGlue)

endif()

add_executable(RGBMedianImageFilter MACOSX_BUNDLE RGBMedianImageFilter.cxx) target_link_libraries(RGBMedianImageFilter

 ${Glue}  ${VTK_LIBRARIES} ${ITK_LIBRARIES})

</syntaxhighlight>

Download and Build RGBMedianImageFilter

Click here to download RGBMedianImageFilter. and its CMakeLists.txt file. Once the tarball RGBMedianImageFilter.tar has been downloaded and extracted,

cd RGBMedianImageFilter/build 

• If ITK is installed:

cmake ..

• If ITK is not installed but compiled on your system, you will need to specify the path to your ITK build:

cmake -DITK_DIR:PATH=/home/me/itk_build ..

Build the project,

make

and run it:

./RGBMedianImageFilter

WINDOWS USERS PLEASE NOTE: Be sure to add the VTK and ITK bin directories to your path. This will resolve the VTK and ITK dll's at run time.

Building All of the Examples

Many of the examples in the ITK Wiki Examples Collection require VTK. You can build all of the the examples by following these instructions. If you are a new VTK user, you may want to try the Superbuild which will build a proper ITK and VTK.

ItkVtkGlue

ITK >= 4

For examples that use QuickView (which depends on VTK), you must have built ITK with Module_ITKVtkGlue=ON.

ITK < 4

Some of the ITK Examples require VTK to display the images. If you download the entire ITK Wiki Examples Collection, the ItkVtkGlue directory will be included and configured. If you wish to just build a few examples, then you will need to download ItkVtkGlue and build it. When you run cmake it will ask you to specify the location of the ItkVtkGlue binary directory.