ImageAccumulateGreyscale

VTKExamples/Cxx/Images/ImageAccumulateGreyscale


Code

ImageAccumulateGreyscale.cxx

#include <vtkSmartPointer.h>

#include <vtkImageReader2Factory.h>
#include <vtkImageReader2.h>
#include <vtkActor.h>
#include <vtkBarChartActor.h>
#include <vtkFieldData.h>
#include <vtkImageAccumulate.h>
#include <vtkImageData.h>
#include <vtkImageExtractComponents.h>
#include <vtkIntArray.h>
#include <vtkLegendBoxActor.h>
#include <vtkProperty2D.h>
#include <vtkRenderer.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkImageMagnitude.h>
#include <vtkNamedColors.h>

int main( int argc, char *argv[] )
{
  // Handle the arguments
  if( argc < 2 )
  {
    std::cout << "Required arguments: filename" << std::endl;
    return EXIT_FAILURE;
  }

  vtkSmartPointer<vtkImageReader2Factory> readerFactory =
    vtkSmartPointer<vtkImageReader2Factory>::New();
  vtkImageReader2 *reader = readerFactory->CreateImageReader2(argv[1]);
  reader->SetFileName(argv[1]);

  vtkSmartPointer<vtkImageMagnitude> magnitude =
    vtkSmartPointer<vtkImageMagnitude>::New();
  magnitude->SetInputConnection(reader->GetOutputPort());

  vtkSmartPointer<vtkNamedColors> colors =
    vtkSmartPointer<vtkNamedColors>::New();

  vtkSmartPointer<vtkIntArray> frequencies =
    vtkSmartPointer<vtkIntArray>::New();

  vtkSmartPointer<vtkImageAccumulate> histogram =
    vtkSmartPointer<vtkImageAccumulate>::New();
  histogram->SetInputConnection(magnitude->GetOutputPort());
  histogram->SetComponentExtent(0,255,0,0,0,0);
  histogram->SetComponentOrigin(0,0,0);
  histogram->SetComponentSpacing(1,0,0);
  histogram->IgnoreZeroOn();
  histogram->Update();

  int numberOfTuples = 64;
  frequencies->SetNumberOfComponents(1);
  frequencies->SetNumberOfTuples(numberOfTuples);
  vtkIdType* output = static_cast<vtkIdType*>(histogram->GetOutput()->GetScalarPointer());

  for(int j = 0; j < numberOfTuples; ++j)
  {
    frequencies->SetTuple1(j, *output++);
  }

  vtkSmartPointer<vtkDataObject> dataObject =
    vtkSmartPointer<vtkDataObject>::New();

  dataObject->GetFieldData()->AddArray( frequencies );

  // Create a vtkBarChartActor
  vtkSmartPointer<vtkBarChartActor> barChart =
    vtkSmartPointer<vtkBarChartActor>::New();

  barChart->SetInput(dataObject);
  barChart->SetTitle("Histogram");
  barChart->GetPositionCoordinate()->SetValue(0.1,0.05,0.0);
  barChart->GetPosition2Coordinate()->SetValue(0.95,0.85,0.0);
  barChart->GetProperty()->SetColor(colors->GetColor3d("Banana").GetData());
  barChart->GetLegendActor()->SetNumberOfEntries(
    dataObject->GetFieldData()->GetArray(0)->GetNumberOfTuples());
  barChart->LegendVisibilityOff();
  barChart->LabelVisibilityOff();

  int count = 0;
  for(int i = 0; i < numberOfTuples; ++i)
  {
    barChart->SetBarColor( count++, colors->GetColor3d("Tomato").GetData());
  }

  // Visualize the histogram
  vtkSmartPointer<vtkRenderer> renderer =
    vtkSmartPointer<vtkRenderer>::New();
  renderer->AddActor(barChart);
  renderer->SetBackground(colors->GetColor3d("Peacock").GetData());
  vtkSmartPointer<vtkRenderWindow> renderWindow =
    vtkSmartPointer<vtkRenderWindow>::New();
  renderWindow->AddRenderer(renderer);
  renderWindow->SetSize(640, 480);

  vtkSmartPointer<vtkRenderWindowInteractor> interactor =
    vtkSmartPointer<vtkRenderWindowInteractor>::New();
  interactor->SetRenderWindow(renderWindow);

  // Initialize the event loop and then start it
  interactor->Initialize();
  interactor->Start();

  reader->Delete();
  return  EXIT_SUCCESS;
}

CMakeLists.txt

cmake_minimum_required(VERSION 2.8)

PROJECT(ImageAccumulateGreyscale)

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

add_executable(ImageAccumulateGreyscale MACOSX_BUNDLE ImageAccumulateGreyscale.cxx )

target_link_libraries(ImageAccumulateGreyscale ${VTK_LIBRARIES})

Download and Build ImageAccumulateGreyscale

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

cd ImageAccumulateGreyscale/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:

./ImageAccumulateGreyscale

WINDOWS USERS

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