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HybridMedianComparison

vtk-examples/Cxx/ImageProcessing/HybridMedianComparison

Description

Comparison of median and hybrid-median filters. The hybrid filter preserves corners and thin lines, better than the median filter. The lower patterns represent the three neighborhoods used to compute the hybrid median.

Info

See this figure in Chapter 10 the VTK Textbook.

Other languages

See (Python)

Question

If you have a question about this example, please use the VTK Discourse Forum

Code

HybridMedianComparison.cxx

#include <vtkCamera.h>
#include <vtkDataArray.h>
#include <vtkImageActor.h>
#include <vtkImageCast.h>
#include <vtkImageData.h>
#include <vtkImageHybridMedian2D.h>
#include <vtkImageMapper3D.h>
#include <vtkImageMathematics.h>
#include <vtkImageMedian3D.h>
#include <vtkImageNoiseSource.h>
#include <vtkImageProperty.h>
#include <vtkImageReader2.h>
#include <vtkImageReader2Factory.h>
#include <vtkImageThreshold.h>
#include <vtkInteractorStyleImage.h>
#include <vtkNew.h>
#include <vtkPointData.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkRenderer.h>
#include <vtkSmartPointer.h>

#include <vector>

namespace {
void AddShotNoise(vtkImageData* inputImage, vtkImageData* outputImage,
                  double noiseAmplitude, double noiseFraction, int extent[6]);
}

int main(int argc, char* argv[])
{
  // Verify input arguments.
  if (argc != 2)
  {
    std::cout << "Usage: " << argv[0] << " Filename e.g. TestPattern.png"
              << std::endl;
    return EXIT_FAILURE;
  }

  // Read the image
  vtkNew<vtkImageReader2Factory> readerFactory;
  vtkSmartPointer<vtkImageReader2> reader;
  reader.TakeReference(readerFactory->CreateImageReader2(argv[1]));
  reader->SetFileName(argv[1]);
  reader->Update();

  int scalarRange[2];
  scalarRange[0] =
      reader->GetOutput()->GetPointData()->GetScalars()->GetRange()[0];
  scalarRange[1] =
      reader->GetOutput()->GetPointData()->GetScalars()->GetRange()[1];
  std::cout << "Range: " << scalarRange[0] << ", " << scalarRange[1]
            << std::endl;
  int middleSlice = (reader->GetOutput()->GetExtent()[5] -
                     reader->GetOutput()->GetExtent()[4]) /
      2;

  // Work with double images
  vtkNew<vtkImageCast> cast;
  cast->SetInputConnection(reader->GetOutputPort());
  cast->SetOutputScalarTypeToDouble();
  cast->Update();

  vtkNew<vtkImageData> originalData;
  originalData->DeepCopy(cast->GetOutput());

  vtkNew<vtkImageData> noisyData;

  AddShotNoise(originalData, noisyData, 2000.0, .1,
               reader->GetOutput()->GetExtent());
  vtkNew<vtkImageMedian3D> median;
  median->SetInputData(noisyData);
  median->SetKernelSize(5, 5, 1);

  vtkNew<vtkImageHybridMedian2D> hybridMedian1;
  hybridMedian1->SetInputData(noisyData);
  vtkNew<vtkImageHybridMedian2D> hybridMedian;
  hybridMedian->SetInputConnection(hybridMedian1->GetOutputPort());

  int colorWindow = (scalarRange[1] - scalarRange[0]);
  int colorLevel = colorWindow / 2;
  vtkNew<vtkImageActor> originalActor;
  originalActor->GetMapper()->SetInputData(originalData);
  originalActor->GetProperty()->SetColorWindow(colorWindow);
  originalActor->GetProperty()->SetColorLevel(colorLevel);
  originalActor->GetProperty()->SetInterpolationTypeToNearest();
  originalActor->SetDisplayExtent(
      reader->GetDataExtent()[0], reader->GetDataExtent()[1],
      reader->GetDataExtent()[2], reader->GetDataExtent()[3], middleSlice,
      middleSlice);

  vtkNew<vtkImageActor> noisyActor;
  noisyActor->GetMapper()->SetInputData(noisyData);
  noisyActor->GetProperty()->SetColorWindow(colorWindow);
  noisyActor->GetProperty()->SetColorLevel(colorLevel);
  noisyActor->GetProperty()->SetInterpolationTypeToNearest();
  noisyActor->SetDisplayExtent(originalActor->GetDisplayExtent());

  vtkNew<vtkImageActor> hybridMedianActor;
  hybridMedianActor->GetMapper()->SetInputConnection(
      hybridMedian->GetOutputPort());
  hybridMedianActor->GetProperty()->SetColorWindow(colorWindow);
  hybridMedianActor->GetProperty()->SetColorLevel(colorLevel);
  hybridMedianActor->GetProperty()->SetInterpolationTypeToNearest();
  hybridMedianActor->SetDisplayExtent(originalActor->GetDisplayExtent());

  vtkNew<vtkImageActor> medianActor;
  medianActor->GetMapper()->SetInputConnection(median->GetOutputPort());
  medianActor->GetProperty()->SetColorWindow(colorWindow);
  medianActor->GetProperty()->SetColorLevel(colorLevel);
  medianActor->GetProperty()->SetInterpolationTypeToNearest();
  medianActor->SetDisplayExtent(originalActor->GetDisplayExtent());

  // Setup renderers
  vtkNew<vtkRenderer> originalRenderer;
  originalRenderer->AddActor(originalActor);
  vtkNew<vtkRenderer> noisyRenderer;
  noisyRenderer->AddActor(noisyActor);
  vtkNew<vtkRenderer> hybridRenderer;
  hybridRenderer->AddActor(hybridMedianActor);
  vtkNew<vtkRenderer> medianRenderer;
  medianRenderer->AddActor(medianActor);

  std::vector<vtkSmartPointer<vtkRenderer>> renderers;
  renderers.push_back(originalRenderer);
  renderers.push_back(noisyRenderer);
  renderers.push_back(hybridRenderer);
  renderers.push_back(medianRenderer);

  // Setup viewports for the renderers.
  int rendererSize = 400;
  unsigned int xGridDimensions = 2;
  unsigned int yGridDimensions = 2;

  vtkNew<vtkRenderWindow> renderWindow;
  renderWindow->SetSize(rendererSize * xGridDimensions,
                        rendererSize * yGridDimensions);
  for (int row = 0; row < static_cast<int>(yGridDimensions); row++)
  {
    for (int col = 0; col < static_cast<int>(xGridDimensions); col++)
    {
      int index = row * xGridDimensions + col;
      // (xmin, ymin, xmax, ymax)
      double viewport[4] = {
          static_cast<double>(col) / xGridDimensions,
          static_cast<double>(yGridDimensions - (row + 1)) / yGridDimensions,
          static_cast<double>(col + 1) / xGridDimensions,
          static_cast<double>(yGridDimensions - row) / yGridDimensions};
      renderers[index]->SetViewport(viewport);
      renderWindow->AddRenderer(renderers[index]);
    }
  }
  renderWindow->SetWindowName("HybridMedianComparison");

  vtkNew<vtkRenderWindowInteractor> renderWindowInteractor;
  vtkNew<vtkInteractorStyleImage> style;

  renderWindowInteractor->SetInteractorStyle(style);
  renderWindowInteractor->SetRenderWindow(renderWindow);

  // Renderers share one camera.
  renderWindow->Render();
  renderers[0]->GetActiveCamera()->Dolly(1.5);
  renderers[0]->ResetCameraClippingRange();

  for (size_t r = 1; r < renderers.size(); ++r)
  {
    renderers[r]->SetActiveCamera(renderers[0]->GetActiveCamera());
  }
  renderWindowInteractor->Initialize();
  renderWindowInteractor->Start();

  return EXIT_SUCCESS;
}
namespace {
void AddShotNoise(vtkImageData* inputImage, vtkImageData* outputImage,
                  double noiseAmplitude, double noiseFraction, int extent[6])
{
  vtkNew<vtkImageNoiseSource> shotNoiseSource;
  shotNoiseSource->SetWholeExtent(extent);
  shotNoiseSource->SetMinimum(0.0);
  shotNoiseSource->SetMaximum(1.0);

  vtkNew<vtkImageThreshold> shotNoiseThresh1;
  shotNoiseThresh1->SetInputConnection(shotNoiseSource->GetOutputPort());
  shotNoiseThresh1->ThresholdByLower(1.0 - noiseFraction);
  shotNoiseThresh1->SetInValue(0);
  shotNoiseThresh1->SetOutValue(noiseAmplitude);

  vtkNew<vtkImageThreshold> shotNoiseThresh2;
  shotNoiseThresh2->SetInputConnection(shotNoiseSource->GetOutputPort());
  shotNoiseThresh2->ThresholdByLower(noiseFraction);
  shotNoiseThresh2->SetInValue(1.0 - noiseAmplitude);
  shotNoiseThresh2->SetOutValue(0.0);

  vtkNew<vtkImageMathematics> shotNoise;
  shotNoise->SetInputConnection(0, shotNoiseThresh1->GetOutputPort());
  shotNoise->SetInputConnection(1, shotNoiseThresh2->GetOutputPort());
  shotNoise->SetOperationToAdd();

  vtkNew<vtkImageMathematics> add;
  add->SetInputData(0, inputImage);
  add->SetInputConnection(1, shotNoise->GetOutputPort());
  add->SetOperationToAdd();
  add->Update();
  outputImage->DeepCopy(add->GetOutput());
}
} // namespace

CMakeLists.txt

cmake_minimum_required(VERSION 3.12 FATAL_ERROR)

project(HybridMedianComparison)

find_package(VTK COMPONENTS 
)

if (NOT VTK_FOUND)
  message(FATAL_ERROR "HybridMedianComparison: Unable to find the VTK build folder.")
endif()

# Prevent a "command line is too long" failure in Windows.
set(CMAKE_NINJA_FORCE_RESPONSE_FILE "ON" CACHE BOOL "Force Ninja to use response files.")
add_executable(HybridMedianComparison MACOSX_BUNDLE HybridMedianComparison.cxx )
  target_link_libraries(HybridMedianComparison PRIVATE ${VTK_LIBRARIES}
)
# vtk_module_autoinit is needed
vtk_module_autoinit(
  TARGETS HybridMedianComparison
  MODULES ${VTK_LIBRARIES}
)

Download and Build HybridMedianComparison

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

cd HybridMedianComparison/build

If VTK is installed:

cmake ..

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

cmake -DVTK_DIR:PATH=/home/me/vtk_build ..

Build the project:

make

and run it:

./HybridMedianComparison

WINDOWS USERS

Be sure to add the VTK bin directory to your path. This will resolve the VTK dll's at run time.