# RGBToHSI

VTKExamples/Cxx/Images/RGBToHSI

### Description

Convert RGB channels to HSI channels. See this article for a description of the HSI colormodel.

Seealso

RGBToYIQ and RGBToHSV

### Code

RGBToHSI.cxx

    #include <vtkSmartPointer.h>
    #include <vtkImageRGBToHSI.h>

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

    int main(int argc, char *argv[])
    {
      // Verify command line arguments
      if(argc != 2)
      {
        std::cerr << "Usage: " << argv[0] << "image" << std::endl;
        return EXIT_FAILURE;
      }

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

      vtkSmartPointer<vtkImageRGBToHSI> hsiFilter =
        vtkSmartPointer<vtkImageRGBToHSI>::New();
      hsiFilter->SetInputConnection(reader->GetOutputPort());

      vtkSmartPointer<vtkImageExtractComponents> extractHFilter =
        vtkSmartPointer<vtkImageExtractComponents>::New();
      extractHFilter->SetInputConnection(hsiFilter->GetOutputPort());
      extractHFilter->SetComponents(0);

      vtkSmartPointer<vtkImageExtractComponents> extractSFilter =
        vtkSmartPointer<vtkImageExtractComponents>::New();
      extractSFilter->SetInputConnection(hsiFilter->GetOutputPort());
      extractSFilter->SetComponents(1);

      vtkSmartPointer<vtkImageExtractComponents> extractIFilter =
        vtkSmartPointer<vtkImageExtractComponents>::New();
      extractIFilter->SetInputConnection(hsiFilter->GetOutputPort());
      extractIFilter->SetComponents(2);

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

      vtkSmartPointer<vtkImageActor> hActor =
        vtkSmartPointer<vtkImageActor>::New();
      hActor->GetMapper()->SetInputConnection(
        extractHFilter->GetOutputPort());

      vtkSmartPointer<vtkImageActor> sActor =
        vtkSmartPointer<vtkImageActor>::New();
      sActor->GetMapper()->SetInputConnection(
        extractSFilter->GetOutputPort());

      vtkSmartPointer<vtkImageActor> iActor =
        vtkSmartPointer<vtkImageActor>::New();
      iActor->GetMapper()->SetInputConnection(
        extractIFilter->GetOutputPort());

      // Define viewport ranges
      // (xmin, ymin, xmax, ymax)
      double inputViewport[4] = {0.0, 0.0, 0.25, 1.0};
      double hViewport[4] = {0.25, 0.0, 0.5, 1.0};
      double sViewport[4] = {0.5, 0.0, 0.75, 1.0};
      double iViewport[4] = {0.75, 0.0, 1.0, 1.0};

      // Shared camera
      vtkSmartPointer<vtkCamera> sharedCamera =
        vtkSmartPointer<vtkCamera>::New();

      // Setup renderers
      vtkSmartPointer<vtkNamedColors> colors =
        vtkSmartPointer<vtkNamedColors>::New();
      vtkSmartPointer<vtkRenderer> inputRenderer =
        vtkSmartPointer<vtkRenderer>::New();
      inputRenderer->SetViewport(inputViewport);
      inputRenderer->AddActor(inputActor);
      inputRenderer->SetActiveCamera(sharedCamera);
      inputRenderer->SetBackground(colors->GetColor3d("Tomato").GetData());

      vtkSmartPointer<vtkRenderer> hRenderer =
        vtkSmartPointer<vtkRenderer>::New();
      hRenderer->SetViewport(hViewport);
      hRenderer->AddActor(hActor);
      hRenderer->SetActiveCamera(sharedCamera);
      hRenderer->SetBackground(colors->GetColor3d("Gainsboro").GetData());

      vtkSmartPointer<vtkRenderer> sRenderer =
        vtkSmartPointer<vtkRenderer>::New();
      sRenderer->SetViewport(sViewport);
      sRenderer->AddActor(sActor);
      sRenderer->SetActiveCamera(sharedCamera);
      sRenderer->SetBackground(colors->GetColor3d("LightGrey").GetData());

      vtkSmartPointer<vtkRenderer> iRenderer =
        vtkSmartPointer<vtkRenderer>::New();
      iRenderer->SetViewport(iViewport);
      iRenderer->AddActor(iActor);
      iRenderer->SetActiveCamera(sharedCamera);
      iRenderer->SetBackground(colors->GetColor3d("Silver").GetData());

      // Setup render window
      vtkSmartPointer<vtkRenderWindow> renderWindow =
        vtkSmartPointer<vtkRenderWindow>::New();
      renderWindow->SetSize(1000, 250);
      renderWindow->AddRenderer(inputRenderer);
      renderWindow->AddRenderer(hRenderer);
      renderWindow->AddRenderer(sRenderer);
      renderWindow->AddRenderer(iRenderer);
      inputRenderer->ResetCamera();

      // 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();

      reader->Delete();
      return EXIT_SUCCESS;
    }

### CMakeLists.txt

    cmake_minimum_required(VERSION 2.8)

    PROJECT(RGBToHSI)

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

    add_executable(RGBToHSI MACOSX_BUNDLE RGBToHSI.cxx )

    target_link_libraries(RGBToHSI ${VTK_LIBRARIES})

### Download and Build RGBToHSI

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

    cd RGBToHSI/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:

    ./RGBToHSI

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.