ITK/Examples/EdgesAndGradients/GradientMagnitudeImageFilter

GradientMagnitudeImageFilter.cxx

#include "itkImage.h"
#include "itkImageFileReader.h"
#include "itkImageFileWriter.h"
#include "itkRescaleIntensityImageFilter.h"
#include "itkGradientMagnitudeImageFilter.h"

#include <itkImageToVTKImageFilter.h>

#include "vtkImageViewer.h"
#include "vtkRenderWindowInteractor.h"
#include "vtkSmartPointer.h"
#include "vtkImageActor.h"
#include "vtkInteractorStyleImage.h"
#include "vtkRenderer.h"

int main(int argc, char * argv[])
{
  // Verify command line arguments
  if( argc < 2 )
    {
	  std::cerr << "Usage: " << std::endl;
	  std::cerr << argv[0] << "inputImageFile" << std::endl;
	  return EXIT_FAILURE;
    }

  // Parse command line arguments
  std::string inputFilename = argv[1];

  // Setup types
  typedef itk::Image< float,  2 >   FloatImageType;
  typedef itk::Image< unsigned char, 2 >   UnsignedCharImageType;

  typedef itk::ImageFileReader< UnsignedCharImageType >  readerType;

  typedef itk::GradientMagnitudeImageFilter<
		  UnsignedCharImageType, FloatImageType >  filterType;

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

  // Create and setup a gradient filter
  filterType::Pointer gradientFilter = filterType::New();
  gradientFilter->SetInput( reader->GetOutput() );
  gradientFilter->Update();

  // To write the gradient image file, we must rescale the gradient values
  // to a reasonable range
  typedef itk::RescaleIntensityImageFilter<
		  FloatImageType, UnsignedCharImageType > rescaleFilterType;

  rescaleFilterType::Pointer rescaler = rescaleFilterType::New();
  rescaler->SetOutputMinimum(0);
  rescaler->SetOutputMaximum(255);
  rescaler->SetInput( gradientFilter->GetOutput() );
  rescaler->Update();
  
  typedef itk::ImageToVTKImageFilter<UnsignedCharImageType> ConnectorType;
  ConnectorType::Pointer originalConnector = ConnectorType::New();
  originalConnector->SetInput(reader->GetOutput());

  vtkSmartPointer<vtkImageActor> originalActor =
    vtkSmartPointer<vtkImageActor>::New();
  originalActor->SetInput(originalConnector->GetOutput());

  typedef itk::ImageToVTKImageFilter<UnsignedCharImageType> ConnectorType;
  ConnectorType::Pointer gradientMagnitudeConnector = ConnectorType::New();
  gradientMagnitudeConnector->SetInput(rescaler->GetOutput());

  vtkSmartPointer<vtkImageActor> gradientMagnitudeActor =
    vtkSmartPointer<vtkImageActor>::New();
  gradientMagnitudeActor->SetInput(gradientMagnitudeConnector->GetOutput());

  // Define viewport ranges
  // (xmin, ymin, xmax, ymax)
  double leftViewport[4] = {0.0, 0.0, 0.5, 1.0};
  double rightViewport[4] = {0.5, 0.0, 1.0, 1.0};

  // Setup both renderers
  vtkSmartPointer<vtkRenderWindow> renderWindow =
    vtkSmartPointer<vtkRenderWindow>::New();
  renderWindow->SetSize(600,300);

  vtkSmartPointer<vtkRenderer> leftRenderer =
    vtkSmartPointer<vtkRenderer>::New();
  renderWindow->AddRenderer(leftRenderer);
  leftRenderer->SetViewport(leftViewport);
  
  vtkSmartPointer<vtkRenderer> rightRenderer =
    vtkSmartPointer<vtkRenderer>::New();
  renderWindow->AddRenderer(rightRenderer);
  rightRenderer->SetViewport(rightViewport);

  leftRenderer->AddActor(originalActor);
  rightRenderer->AddActor(gradientMagnitudeActor);

  vtkSmartPointer<vtkRenderWindowInteractor> renderWindowInteractor =
    vtkSmartPointer<vtkRenderWindowInteractor>::New();
  vtkSmartPointer<vtkInteractorStyleImage> style =
    vtkSmartPointer<vtkInteractorStyleImage>::New();

  renderWindowInteractor->SetInteractorStyle(style);

  renderWindowInteractor->SetRenderWindow(renderWindow);
  renderWindowInteractor->Initialize();

  renderWindowInteractor->Start();

  return EXIT_SUCCESS;
}

CMakeLists.txt

cmake_minimum_required(VERSION 2.6)

PROJECT(GradientMagnitudeImageFilter)

FIND_PACKAGE(ITK REQUIRED)
INCLUDE(${ITK_USE_FILE})

ADD_EXECUTABLE(GradientMagnitudeImageFilter GradientMagnitudeImageFilter.cxx)
TARGET_LINK_LIBRARIES(Gradient ITKNumerics ITKIO ITKAlgorithms)