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# ImageMirrorPad

VTKEx/Cxx/Images/ImageMirrorPad

### Description

This example shows how to enlarge an image and fill in the padded edges by mirroring the original pixels.

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

ImageMirrorPad.cxx

    #include <vtkSmartPointer.h>
    #include <vtkImageData.h>
    #include <vtkImageMapper3D.h>
    #include <vtkImageCanvasSource2D.h>
    #include <vtkImageMirrorPad.h>
    #include <vtkRenderWindow.h>
    #include <vtkRenderWindowInteractor.h>
    #include <vtkProperty.h>
    #include <vtkRenderer.h>
    #include <vtkImageActor.h>

    int main(int, char *[])
    {
      // Create an image
      vtkSmartPointer<vtkImageCanvasSource2D> source =
        vtkSmartPointer<vtkImageCanvasSource2D>::New();
      source->SetExtent(0, 20, 0, 20, 0, 0);
      source->SetScalarTypeToUnsignedChar();
      source->SetDrawColor(0.0, 0.0, 0.0, 1.0);
      source->FillBox(-VTK_INT_MAX, VTK_INT_MAX, -VTK_INT_MAX, VTK_INT_MAX);
      source->SetDrawColor(255.0, 0.0, 0.0, 0.5);
      source->DrawCircle(10, 10, 5);
      source->Update();

      vtkSmartPointer<vtkImageMirrorPad> mirrorPadFilter =
        vtkSmartPointer<vtkImageMirrorPad>::New();
      mirrorPadFilter->SetInputConnection(source->GetOutputPort());
      mirrorPadFilter->SetOutputWholeExtent(-10, 30, -10, 30, 0, 0);
      mirrorPadFilter->Update();

      // Create an actor
      vtkSmartPointer<vtkImageActor> actor =
        vtkSmartPointer<vtkImageActor>::New();
      actor->GetMapper()->SetInputConnection(
        mirrorPadFilter->GetOutputPort());

      // Visualize
      vtkSmartPointer<vtkRenderer> renderer =
          vtkSmartPointer<vtkRenderer>::New();
      renderer->AddActor(actor);
      renderer->ResetCamera();

      vtkSmartPointer<vtkRenderWindow> renderWindow =
        vtkSmartPointer<vtkRenderWindow>::New();
      renderWindow->AddRenderer ( renderer );

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

      renderWindowInteractor->SetRenderWindow ( renderWindow );
      renderWindow->Render();
      renderWindowInteractor->Initialize();

      renderWindowInteractor->Start();

      return EXIT_SUCCESS;
    }

### CMakeLists.txt

    cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

    project(ImageMirrorPad)

    find_package(VTK COMPONENTS
      vtkCommonCore
      vtkCommonDataModel
      vtkImagingCore
      vtkImagingSources
      vtkInteractionStyle
      vtkRenderingContextOpenGL2
      vtkRenderingCore
      vtkRenderingFreeType
      vtkRenderingGL2PSOpenGL2
      vtkRenderingOpenGL2 QUIET)
    if (NOT VTK_FOUND)
      message("Skipping ImageMirrorPad: ${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(ImageMirrorPad MACOSX_BUNDLE ImageMirrorPad.cxx )
      target_link_libraries(ImageMirrorPad PRIVATE ${VTK_LIBRARIES})
    else ()
      # include all components
      add_executable(ImageMirrorPad MACOSX_BUNDLE ImageMirrorPad.cxx )
      target_link_libraries(ImageMirrorPad PRIVATE ${VTK_LIBRARIES})
      # vtk_module_autoinit is needed
      vtk_module_autoinit(
        TARGETS ImageMirrorPad
        MODULES ${VTK_LIBRARIES}
        )
    endif ()

### Download and Build ImageMirrorPad

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

    cd ImageMirrorPad/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:

    ./ImageMirrorPad

WINDOWS USERS

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