ImageAccumulateGreyscale
VTKExamples/Cxx/Images/ImageAccumulateGreyscale
Code
ImageAccumulateGreyscale.cxx
#include <vtkActor.h>
#include <vtkBarChartActor.h>
#include <vtkFieldData.h>
#include <vtkImageAccumulate.h>
#include <vtkImageData.h>
#include <vtkImageExtractComponents.h>
#include <vtkIntArray.h>
#include <vtkJPEGReader.h>
#include <vtkLegendBoxActor.h>
#include <vtkProperty2D.h>
#include <vtkRenderer.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkSmartPointer.h>
#include <vtkImageMagnitude.h>
int main( int argc, char *argv[] )
{
// Handle the arguments
if( argc < 2 )
{
std::cout << "Required arguments: filename.jpg" << std::endl;
return EXIT_FAILURE;
}
// Read a jpeg image
vtkSmartPointer<vtkJPEGReader> reader =
vtkSmartPointer<vtkJPEGReader>::New();
reader->SetFileName( argv[1] );
reader->Update();
vtkSmartPointer<vtkImageMagnitude> magnitude =
vtkSmartPointer<vtkImageMagnitude>::New();
magnitude->SetInputConnection(reader->GetOutputPort());
magnitude->Update();
double red[3] = {1, 0, 0 };
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();
frequencies->SetNumberOfComponents(1);
frequencies->SetNumberOfTuples(256);
int* output = static_cast<int*>(histogram->GetOutput()->GetScalarPointer());
for(int j = 0; j < 256; ++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(0.05,0.05,0.0);
barChart->GetPosition2Coordinate()->SetValue(0.95,0.85,0.0);
barChart->GetProperty()->SetColor(1,1,1);
barChart->GetLegendActor()->SetNumberOfEntries(dataObject->GetFieldData()->GetArray(0)->GetNumberOfTuples());
barChart->LegendVisibilityOff();
barChart->LabelVisibilityOff();
int count = 0;
for(int i = 0; i < 256; ++i)
{
barChart->SetBarColor( count++, red );
}
// Visualize the histogram
vtkSmartPointer<vtkRenderer> renderer =
vtkSmartPointer<vtkRenderer>::New();
renderer->AddActor(barChart);
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();
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 PLEASE NOTE: Be sure to add the VTK bin directory to your path. This will resolve the VTK dll's at run time.