# ImageCheckerboard

VTKExamples/Cxx/Images/ImageCheckerboard

### Description

This example compares two images using a checkerboard pattern.

### Code

ImageCheckerboard.cxx

    #include <vtkImageCheckerboard.h>
    #include <vtkSmartPointer.h>

    #include <vtkImageReader2Factory.h>
    #include <vtkImageReader2.h>
    #include <vtkRenderWindow.h>
    #include <vtkRenderWindowInteractor.h>
    #include <vtkRenderer.h>
    #include <vtkImageData.h>
    #include <vtkImageViewer2.h>
    #include <vtkNamedColors.h>

    int main ( int argc, char* argv[] )
    {
      // Verify input arguments
      if ( argc != 3 )
      {
        std::cerr << "Usage: " << argv[0]
                  << " Input1Filename Input2Filename" << std::endl;
        return EXIT_FAILURE;
      }

      // Read the images
      vtkSmartPointer<vtkImageReader2Factory> readerFactory =
        vtkSmartPointer<vtkImageReader2Factory>::New();
      vtkImageReader2 *reader1 = readerFactory->CreateImageReader2(argv[1]);
      reader1->SetFileName(argv[1]);

      vtkImageReader2 *reader2 = readerFactory->CreateImageReader2(argv[2]);
      reader2->SetFileName(argv[2]);

      vtkSmartPointer<vtkImageCheckerboard> checkerboardFilter =
        vtkSmartPointer<vtkImageCheckerboard>::New();
      checkerboardFilter->SetInputConnection(0, reader1->GetOutputPort());
      checkerboardFilter->SetInputConnection(1, reader2->GetOutputPort());
      checkerboardFilter->SetNumberOfDivisions(3,3,1);

      // Visualize
      vtkSmartPointer<vtkRenderWindowInteractor> renderWindowInteractor =
        vtkSmartPointer<vtkRenderWindowInteractor>::New();

      vtkSmartPointer<vtkNamedColors> colors =
        vtkSmartPointer<vtkNamedColors>::New();
      vtkSmartPointer<vtkImageViewer2> imageViewer =
        vtkSmartPointer<vtkImageViewer2>::New();
      imageViewer->SetInputConnection(checkerboardFilter->GetOutputPort());
      imageViewer->SetupInteractor(renderWindowInteractor);
      imageViewer->GetRenderer()->ResetCamera();
      imageViewer->GetRenderer()->SetBackground(
        colors->GetColor3d("Wheat").GetData());
      renderWindowInteractor->Initialize();
      renderWindowInteractor->Start();

      reader1->Delete();
      reader2->Delete();
      return EXIT_SUCCESS;
    }

### CMakeLists.txt

    cmake_minimum_required(VERSION 2.8)

    PROJECT(ImageCheckerboard)

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

    add_executable(ImageCheckerboard MACOSX_BUNDLE ImageCheckerboard.cxx )

    target_link_libraries(ImageCheckerboard ${VTK_LIBRARIES})

### Download and Build ImageCheckerboard

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

    cd ImageCheckerboard/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:

    ./ImageCheckerboard

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.