# ResizeImage

VTKExamples/Cxx/Images/ResizeImage

### Description

Resize an image using a sinc interpolator. Without command line arguments, the example resizes a synthetic image. An image file can be passed on the command lines. The new dimensions can also be passed as well as an integer specifying the window for sinc interpolator. See vtkImageSincInterpolator for details. A -1 turns off interpolation.

Several window functions are provided. See this article for a description og window functions. vtkImageResize maintains the physical size of the image.

Note

This example was inspired by a question asked by Qiang Wang.

Seealso

The paper "Some windows with very good sidelobe behavior" describes the windows implemented in vtkImageSincInterpolator.

### Code

ResizeImage.cxx

    #include <vtkSmartPointer.h>
    #include <vtkImageResize.h>
    #include <vtkImageSincInterpolator.h>

    #include <vtkImageReader2Factory.h>
    #include <vtkImageReader2.h>
    #include <vtkCamera.h>
    #include <vtkImageActor.h>
    #include <vtkImageCanvasSource2D.h>
    #include <vtkImageData.h>
    #include <vtkImageMapper3D.h>
    #include <vtkRenderer.h>
    #include <vtkRenderWindow.h>
    #include <vtkRenderWindowInteractor.h>
    #include <vtkInteractorStyleImage.h>
    #include <vtkNamedColors.h>

    int main(int argc, char *argv[])
    {
      vtkSmartPointer<vtkImageData> imageData;

      int newSize[2] = {200, 10};
      int windowFunction = 0;

      // Verify input arguments
      if ( argc > 1 )
      {
        // Read the image
        vtkSmartPointer<vtkImageReader2Factory> readerFactory =
          vtkSmartPointer<vtkImageReader2Factory>::New();
        vtkImageReader2 *reader = readerFactory->CreateImageReader2(argv[1]);
        reader->SetFileName(argv[1]);
        reader->Update();

        imageData = reader->GetOutput();
        reader->Delete();
        if (argc >3)
        {
          newSize[0] = atoi(argv[2]);
          newSize[1] = atoi(argv[3]);
        }
        if (argc > 4)
        {
          windowFunction = atoi(argv[4]);
        }
      }
      else
      {
        vtkSmartPointer<vtkImageCanvasSource2D> canvasSource =
          vtkSmartPointer<vtkImageCanvasSource2D>::New();
        canvasSource->SetExtent(0, 100, 0, 100, 0, 0);
        canvasSource->SetScalarTypeToUnsignedChar();
        canvasSource->SetNumberOfScalarComponents(3);
        canvasSource->SetDrawColor(127, 127, 100);
        canvasSource->FillBox(0, 100, 0, 100);
        canvasSource->SetDrawColor(100, 255, 255);
        canvasSource->FillTriangle(10, 10, 25, 10, 25, 25);
        canvasSource->SetDrawColor(255, 100, 255);
        canvasSource->FillTube(75, 75, 0, 75, 5.0);
        canvasSource->Update();
        imageData = canvasSource->GetOutput();
      }

      vtkSmartPointer<vtkImageSincInterpolator> interpolator =
        vtkSmartPointer<vtkImageSincInterpolator>::New();
      interpolator->UseWindowParameterOn();
      if (windowFunction >= 0 && windowFunction <= 10)
      {
        interpolator->SetWindowFunction(windowFunction);
      }

      vtkSmartPointer<vtkImageResize> resize =
        vtkSmartPointer<vtkImageResize>::New();
      resize->SetInputData(imageData);
      resize->SetInterpolator(interpolator);
      resize->SetOutputDimensions(newSize[0], newSize[1], 1);
      resize->InterpolateOn();

      if (windowFunction < 0)
      {
        resize->InterpolateOff();
        std::cout << "Using nearest neighbor interpolation" << std::endl;;
      }
      else
      {
        std::cout << "Using window function : "
                  << interpolator->GetWindowFunctionAsString() << std::endl;;
      }

      // Create an image actor to display the image
      vtkSmartPointer<vtkImageActor> imageActor =
        vtkSmartPointer<vtkImageActor>::New();
      imageActor->GetMapper()->SetInputConnection(resize->GetOutputPort());
      imageActor->InterpolateOff();

      // Setup renderer
      vtkSmartPointer<vtkNamedColors> colors =
        vtkSmartPointer<vtkNamedColors>::New();

      vtkSmartPointer<vtkRenderer> renderer =
        vtkSmartPointer<vtkRenderer>::New();
      renderer->AddActor(imageActor);
      renderer->SetBackground(colors->GetColor3d("Burlywood").GetData());
      renderer->ResetCamera();
      renderer->GetActiveCamera()->Dolly(5.0);
      renderer->ResetCameraClippingRange();

      // Setup render window
      vtkSmartPointer<vtkRenderWindow> renderWindow =
        vtkSmartPointer<vtkRenderWindow>::New();
      renderWindow->AddRenderer(renderer);
      renderWindow->SetSize(1280, 1024);

      // Setup render window interactor
      vtkSmartPointer<vtkRenderWindowInteractor> renderWindowInteractor =
        vtkSmartPointer<vtkRenderWindowInteractor>::New();
      vtkSmartPointer<vtkInteractorStyleImage> style =
        vtkSmartPointer<vtkInteractorStyleImage>::New();

      renderWindowInteractor->SetInteractorStyle(style);

      // Render and start interaction
      renderWindowInteractor->SetRenderWindow(renderWindow);
      renderWindowInteractor->Initialize();

      renderWindowInteractor->Start();

      return EXIT_SUCCESS;
    }

### CMakeLists.txt

    cmake_minimum_required(VERSION 2.8)

    PROJECT(ResizeImage)

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

    add_executable(ResizeImage MACOSX_BUNDLE ResizeImage.cxx )

    target_link_libraries(ResizeImage ${VTK_LIBRARIES})

### Download and Build ResizeImage

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

    cd ResizeImage/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:

    ./ResizeImage

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.