# ImageWeightedSum

VTKExamples/Cxx/ImageData/ImageWeightedSum

### Description

Sum multiple images. Images must be of the same size and type.

Other Languages

See (Python)

### Code

ImageWeightedSum.cxx

    #include <vtkImageActor.h>
    #include <vtkImageCanvasSource2D.h>
    #include <vtkImageCast.h>
    #include <vtkImageData.h>
    #include <vtkImageMandelbrotSource.h>
    #include <vtkImageMapper3D.h>
    #include <vtkImageSinusoidSource.h>
    #include <vtkImageWeightedSum.h>
    #include <vtkInteractorStyleImage.h>
    #include <vtkNamedColors.h>
    #include <vtkRenderWindow.h>
    #include <vtkRenderWindowInteractor.h>
    #include <vtkRenderer.h>
    #include <vtkSmartPointer.h>

    #include <array>

    int main(int, char *[]) {
      vtkNew<vtkNamedColors> colors;

      std::array<double, 4> bkgL = {{0.6, 0.5, 0.4, 1.0}};
      std::array<double, 4> bkgC = {{0.1, 0.5, 0.4, 1.0}};
      std::array<double, 4> bkgR = {{0.4, 0.5, 0.6, 1.0}};
      colors->SetColor("leftBkg", bkgL.data());
      colors->SetColor("centreBkg", bkgC.data());
      colors->SetColor("rightBkg", bkgR.data());

      // create an image
      vtkSmartPointer<vtkImageMandelbrotSource> source1 =
          vtkSmartPointer<vtkImageMandelbrotSource>::New();
      source1->SetWholeExtent(0, 255, 0, 255, 0, 0);
      source1->Update();

      vtkSmartPointer<vtkImageCast> source1Double =
          vtkSmartPointer<vtkImageCast>::New();
      source1Double->SetInputConnection(0, source1->GetOutputPort());
      source1Double->SetOutputScalarTypeToDouble();

      vtkSmartPointer<vtkImageSinusoidSource> source2 =
          vtkSmartPointer<vtkImageSinusoidSource>::New();
      source2->SetWholeExtent(0, 255, 0, 255, 0, 0);
      source2->Update();

      vtkSmartPointer<vtkImageWeightedSum> sumFilter =
          vtkSmartPointer<vtkImageWeightedSum>::New();
      sumFilter->SetWeight(0, .8);
      sumFilter->SetWeight(1, .2);
      sumFilter->AddInputConnection(source1Double->GetOutputPort());
      sumFilter->AddInputConnection(source2->GetOutputPort());

      sumFilter->Update();

      vtkSmartPointer<vtkImageCast> source1CastFilter =
          vtkSmartPointer<vtkImageCast>::New();
      source1CastFilter->SetInputConnection(source1->GetOutputPort());
      source1CastFilter->SetOutputScalarTypeToUnsignedChar();
      source1CastFilter->Update();

      vtkSmartPointer<vtkImageCast> source2CastFilter =
          vtkSmartPointer<vtkImageCast>::New();
      source2CastFilter->SetInputConnection(source2->GetOutputPort());
      source2CastFilter->SetOutputScalarTypeToUnsignedChar();
      source2CastFilter->Update();

      vtkSmartPointer<vtkImageCast> summedCastFilter =
          vtkSmartPointer<vtkImageCast>::New();
      summedCastFilter->SetInputConnection(sumFilter->GetOutputPort());
      summedCastFilter->SetOutputScalarTypeToUnsignedChar();
      summedCastFilter->Update();

      // Create actors
      vtkSmartPointer<vtkImageActor> source1Actor =
          vtkSmartPointer<vtkImageActor>::New();
      source1Actor->GetMapper()->SetInputConnection(
          source1CastFilter->GetOutputPort());

      vtkSmartPointer<vtkImageActor> source2Actor =
          vtkSmartPointer<vtkImageActor>::New();
      source2Actor->GetMapper()->SetInputConnection(
          source2CastFilter->GetOutputPort());

      vtkSmartPointer<vtkImageActor> summedActor =
          vtkSmartPointer<vtkImageActor>::New();
      summedActor->GetMapper()->SetInputConnection(
          summedCastFilter->GetOutputPort());

      // There will be one render window
      vtkSmartPointer<vtkRenderWindow> renderWindow =
          vtkSmartPointer<vtkRenderWindow>::New();
      renderWindow->SetSize(600, 300);

      // And one interactor
      vtkSmartPointer<vtkRenderWindowInteractor> interactor =
          vtkSmartPointer<vtkRenderWindowInteractor>::New();
      interactor->SetRenderWindow(renderWindow);

      // Define viewport ranges
      // (xmin, ymin, xmax, ymax)
      double leftViewport[4] = {0.0, 0.0, 0.33, 1.0};
      double centerViewport[4] = {0.33, 0.0, .66, 1.0};
      double rightViewport[4] = {0.66, 0.0, 1.0, 1.0};

      // Setup renderers
      vtkSmartPointer<vtkRenderer> leftRenderer =
          vtkSmartPointer<vtkRenderer>::New();
      renderWindow->AddRenderer(leftRenderer);
      leftRenderer->SetViewport(leftViewport);
      leftRenderer->SetBackground(colors->GetColor3d("leftBkg").GetData());

      vtkSmartPointer<vtkRenderer> centerRenderer =
          vtkSmartPointer<vtkRenderer>::New();
      renderWindow->AddRenderer(centerRenderer);
      centerRenderer->SetViewport(centerViewport);
      centerRenderer->SetBackground(colors->GetColor3d("centreBkg").GetData());

      vtkSmartPointer<vtkRenderer> rightRenderer =
          vtkSmartPointer<vtkRenderer>::New();
      renderWindow->AddRenderer(rightRenderer);
      rightRenderer->SetViewport(rightViewport);
      rightRenderer->SetBackground(colors->GetColor3d("rightBkg").GetData());

      leftRenderer->AddActor(source1Actor);
      centerRenderer->AddActor(source2Actor);
      rightRenderer->AddActor(summedActor);

      leftRenderer->ResetCamera();
      centerRenderer->ResetCamera();
      rightRenderer->ResetCamera();

      renderWindow->Render();
      interactor->Start();

      return EXIT_SUCCESS;
    }

### CMakeLists.txt

    cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

    project(ImageWeightedSum)

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

### Download and Build ImageWeightedSum

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

    cd ImageWeightedSum/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:

    ./ImageWeightedSum

WINDOWS USERS

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