VTK/Examples/Cxx/Images/ImageAccumulate

ImageAccumulate.cxx

/*
 * In this example, the resulting histogram has 6 pixels (all of them) in the 3rd bin (value = 2) and zero in the rest of the bins
 */
#include <vtkVersion.h>
#include <vtkImageAccumulate.h>
#include <vtkImageData.h>
#include <vtkSmartPointer.h>

static void CreateImage(vtkSmartPointer<vtkImageData> image);

int main(int, char *[] )
{
  vtkSmartPointer<vtkImageData> image = vtkSmartPointer<vtkImageData>::New();
  CreateImage(image);

  vtkSmartPointer<vtkImageAccumulate> imageAccumulate = 
    vtkSmartPointer<vtkImageAccumulate>::New();
#if VTK_MAJOR_VERSION <= 5
  imageAccumulate->SetInputConnection(image->GetProducerPort());
#else
  imageAccumulate->SetInputData(image);
#endif
  imageAccumulate->SetComponentExtent(0,255,0,0,0,0);
  imageAccumulate->SetComponentOrigin(0,0,0);
  imageAccumulate->SetComponentSpacing(1,0,0); // This will count exactly the number of pixels of each color. Use (10,0,0) to make bins of width 10 instead.
  imageAccumulate->Update();

  int dims[3];
  imageAccumulate->GetOutput()->GetDimensions(dims);
  for(vtkIdType bin = 0; bin < dims[0]; ++bin)
   {
   std::cout << *(static_cast<int*>(imageAccumulate->GetOutput()->GetScalarPointer(bin, 0, 0))) << " ";
   }

  std::cout << std::endl;

  double mean[3];
  imageAccumulate->GetMean(mean);
  std::cout << "Mean: " << mean[0] << " " << mean[1] << " " << mean[2] << std::endl;
 
  return  EXIT_SUCCESS;
}

void CreateImage(vtkSmartPointer<vtkImageData> image)
{
  // Specify the size of the image data
  image->SetDimensions(2,3,1);
  //image->SetExtent(0,2,0,3,0,1);
#if VTK_MAJOR_VERSION <= 5
  image->SetNumberOfScalarComponents(1);
  image->SetScalarTypeToDouble();
  image->AllocateScalars();
#else
  image->AllocateScalars(VTK_DOUBLE,1);
#endif
  int* dims = image->GetDimensions();
  // int dims[3]; // can't do this
 
  std::cout << "Dims: " << " x: " << dims[0] << " y: " << dims[1] << " z: " << dims[2] << std::endl;
 
  // Fill every entry of the image data with "2.0"
  for (int z = 0; z < dims[2]; z++)
    {
    for (int y = 0; y < dims[1]; y++)
      {
      for (int x = 0; x < dims[0]; x++)
        {
        double* pixel = static_cast<double*>(image->GetScalarPointer(x,y,z));
        pixel[0] = 2.0;
        }
      }
    }
}

Please try the new VTKExamples website.

CMakeLists.txt

cmake_minimum_required(VERSION 2.8)

PROJECT(ImageAccumulate)

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

add_executable(ImageAccumulate MACOSX_BUNDLE ImageAccumulate.cxx)

if(VTK_LIBRARIES)
  target_link_libraries(ImageAccumulate ${VTK_LIBRARIES})
else()
  target_link_libraries(ImageAccumulate vtkHybrid vtkWidgets)
endif()

Download and Build ImageAccumulate

Click here to download ImageAccumulate. and its CMakeLists.txt file.

Once the tarball ImageAccumulate.tar has been downloaded and extracted,

cd ImageAccumulate/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:

./ImageAccumulate

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.