Skip to content


# ResizeImageDemo

VTKEx/Cxx/Images/ResizeImageDemo

Question

If you have a simple question about this example contact us at VTKExProject If your question is more complex and may require extended discussion, please use the VTK Discourse Forum

### Code

ResizeImageDemo.cxx

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

    #include <vtkActor2D.h>
    #include <vtkCamera.h>
    #include <vtkImageActor.h>
    #include <vtkImageCanvasSource2D.h>
    #include <vtkImageData.h>
    #include <vtkImageMapper3D.h>
    #include <vtkImageReader2.h>
    #include <vtkImageReader2Factory.h>
    #include <vtkInteractorStyleImage.h>
    #include <vtkNamedColors.h>
    #include <vtkRenderWindow.h>
    #include <vtkRenderWindowInteractor.h>
    #include <vtkRenderer.h>
    #include <vtkTextMapper.h>
    #include <vtkTextProperty.h>

    #include <string>
    #include <vector>

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

      double factor = .5;
      int newSize[2];

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

        imageData = reader->GetOutput();
        if (argc > 2)
        {
          factor = atof(argv[2]);
        }
      }
      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();
      }

      std::cout << "Original dimensions: " << imageData->GetDimensions()[0] << ", "
                << imageData->GetDimensions()[1] << std::endl;
      newSize[0] = imageData->GetDimensions()[0] * factor;
      newSize[1] = imageData->GetDimensions()[1] * factor;
      std::cout << "New dimensions: " << newSize[0] << ", " << newSize[1]
                << std::endl;

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

      // One camera for all
      auto camera = vtkSmartPointer<vtkCamera>::New();

      // Create one text property for all
      auto textProperty = vtkSmartPointer<vtkTextProperty>::New();
      textProperty->SetFontSize(20);
      textProperty->SetJustificationToCentered();
      textProperty->SetColor(0.3, 0.3, 0.3);

      // Setup render window
      auto renderWindow = vtkSmartPointer<vtkRenderWindow>::New();

      std::vector<vtkSmartPointer<vtkRenderer>> renderers;
      for (int i = -1; i <= 10; ++i)
      {
        auto interpolator = vtkSmartPointer<vtkImageSincInterpolator>::New();
        auto windowFunction = i;
        interpolator->UseWindowParameterOn();

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

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

        // Create textActors
        auto textMapper = vtkSmartPointer<vtkTextMapper>::New();
        textMapper->SetTextProperty(textProperty);
        if (windowFunction < 0)
        {
          resize->InterpolateOff();
          textMapper->SetInput("Nearest neighbor");
        }
        else
        {
          resize->InterpolateOn();
          interpolator->SetWindowFunction(windowFunction);
          textMapper->SetInput(interpolator->GetWindowFunctionAsString());
        }

        auto textActor = vtkSmartPointer<vtkActor2D>::New();
        textActor->SetMapper(textMapper);
        textActor->SetPosition(100, 16);
        // Setup renderer
        auto renderer = vtkSmartPointer<vtkRenderer>::New();
        renderer->AddActor(imageActor);
        renderer->AddActor(textActor);
        ;
        renderer->SetBackground(colors->GetColor3d("Burlywood").GetData());
        renderer->SetActiveCamera(camera);
        renderer->ResetCamera();
        renderer->GetActiveCamera()->Dolly(5);
        renderer->ResetCameraClippingRange();
        renderers.push_back(renderer);
        renderWindow->AddRenderer(renderer);
      }
      // Setup viewports for the renderers
      int rendererSize = 200;
      unsigned int xGridDimensions = 4;
      unsigned int yGridDimensions = 3;
      renderWindow->SetSize(rendererSize * xGridDimensions,
                            rendererSize * yGridDimensions);
      for (int row = 0; row < static_cast<int>(yGridDimensions); row++)
      {
        for (int col = 0; col < static_cast<int>(xGridDimensions); col++)
        {
          int index = row * xGridDimensions + col;

          // (xmin, ymin, xmax, ymax)
          double viewport[4] = {static_cast<double>(col) * rendererSize /
                                    (xGridDimensions * rendererSize),
                                static_cast<double>(yGridDimensions - (row + 1)) *
                                    rendererSize / (yGridDimensions * rendererSize),
                                static_cast<double>(col + 1) * rendererSize /
                                    (xGridDimensions * rendererSize),
                                static_cast<double>(yGridDimensions - row) *
                                    rendererSize /
                                    (yGridDimensions * rendererSize)};
          renderers[index]->SetViewport(viewport);
        }
      }

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

      renderWindowInteractor->SetInteractorStyle(style);

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

      renderWindowInteractor->Start();

      return EXIT_SUCCESS;
    }

### CMakeLists.txt

    cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

    project(ResizeImageDemo)

    find_package(VTK COMPONENTS
      vtkCommonColor
      vtkCommonCore
      vtkCommonDataModel
      vtkIOImage
      vtkImagingCore
      vtkImagingSources
      vtkInteractionStyle
      vtkRenderingContextOpenGL2
      vtkRenderingCore
      vtkRenderingFreeType
      vtkRenderingGL2PSOpenGL2
      vtkRenderingOpenGL2 QUIET)
    if (NOT VTK_FOUND)
      message("Skipping ResizeImageDemo: ${VTK_NOT_FOUND_MESSAGE}")
      return ()
    endif()
    message (STATUS "VTK_VERSION: ${VTK_VERSION}")
    if (VTK_VERSION VERSION_LESS "8.90.0")
      # old system
      include(${VTK_USE_FILE})
      add_executable(ResizeImageDemo MACOSX_BUNDLE ResizeImageDemo.cxx )
      target_link_libraries(ResizeImageDemo PRIVATE ${VTK_LIBRARIES})
    else ()
      # include all components
      add_executable(ResizeImageDemo MACOSX_BUNDLE ResizeImageDemo.cxx )
      target_link_libraries(ResizeImageDemo PRIVATE ${VTK_LIBRARIES})
      # vtk_module_autoinit is needed
      vtk_module_autoinit(
        TARGETS ResizeImageDemo
        MODULES ${VTK_LIBRARIES}
        )
    endif ()

### Download and Build ResizeImageDemo

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

    cd ResizeImageDemo/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:

    ./ResizeImageDemo

WINDOWS USERS

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