ITK/Examples/ImageProcessing/InvertIntensityImageFilter

This example demonstrates how to invert the intensity of pixels by subtracting each pixel value from a specified maximum value. The output shows the original image and the inverted image.

InvertIntensityImageFilter.cxx

<source lang="cpp">

1. include "itkImage.h"
2. include "itkRescaleIntensityImageFilter.h"
3. include "itkInvertIntensityImageFilter.h"
4. include "itkImageFileReader.h"

1. include "itkImageToVTKImageFilter.h"

1. include "vtkImageViewer.h"
2. include "vtkRenderWindowInteractor.h"
3. include "vtkSmartPointer.h"
4. include "vtkImageActor.h"
5. include "vtkInteractorStyleImage.h"
6. include "vtkRenderer.h"

typedef itk::Image<unsigned char, 2> ImageType;

static void CreateImage(ImageType::Pointer image);

int main(int, char *[]) {

 ImageType::Pointer image = ImageType::New();
 CreateImage(image);

 typedef itk::InvertIntensityImageFilter <ImageType>
   InvertIntensityImageFilterType;

 InvertIntensityImageFilterType::Pointer invertIntensityFilter
   = InvertIntensityImageFilterType::New();
 invertIntensityFilter->SetInput(image);
 invertIntensityFilter->SetMaximum(50);
 invertIntensityFilter->Update();

 // Visualize first image
 typedef itk::ImageToVTKImageFilter<ImageType> ConnectorType;
 ConnectorType::Pointer originalConnector = ConnectorType::New();
 originalConnector->SetInput(image);

 vtkSmartPointer<vtkImageActor> originalActor =
   vtkSmartPointer<vtkImageActor>::New();
 originalActor->SetInput(originalConnector->GetOutput());

 // Visualize inverted image
 ConnectorType::Pointer invertedConnector = ConnectorType::New();
 invertedConnector->SetInput(invertIntensityFilter->GetOutput());

 vtkSmartPointer<vtkImageActor> invertedActor =
   vtkSmartPointer<vtkImageActor>::New();
 invertedActor->SetInput(invertedConnector->GetOutput());

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

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

 // Define viewport ranges
 // (xmin, ymin, xmax, ymax)
 double leftViewport[4] = {0.0, 0.0, 0.5, 1.0};
 double rightViewport[4] = {0.5, 0.0, 1.0, 1.0};

 // Setup both renderers
 vtkSmartPointer<vtkRenderer> leftRenderer =
   vtkSmartPointer<vtkRenderer>::New();
 renderWindow->AddRenderer(leftRenderer);
 leftRenderer->SetViewport(leftViewport);
 leftRenderer->SetBackground(.6, .5, .4);

 vtkSmartPointer<vtkRenderer> rightRenderer =
   vtkSmartPointer<vtkRenderer>::New();
 renderWindow->AddRenderer(rightRenderer);
 rightRenderer->SetViewport(rightViewport);
 rightRenderer->SetBackground(.4, .5, .6);

 // Add the sphere to the left and the cube to the right
 leftRenderer->AddActor(originalActor);
 rightRenderer->AddActor(invertedActor);

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

 renderWindow->Render();

 vtkSmartPointer<vtkInteractorStyleImage> style =
   vtkSmartPointer<vtkInteractorStyleImage>::New();
 interactor->SetInteractorStyle(style);

 interactor->Start();

 return EXIT_SUCCESS;

}

void CreateImage(ImageType::Pointer image) {

 // Create an image
 ImageType::RegionType region;
 ImageType::IndexType start;
 start[0] = 0;
 start[1] = 0;

 ImageType::SizeType size;
 unsigned int NumRows = 200;
 unsigned int NumCols = 300;
 size[0] = NumRows;
 size[1] = NumCols;

 region.SetSize(size);
 region.SetIndex(start);

 image->SetRegions(region);
 image->Allocate();

 // Make a square
 for(unsigned int r = 40; r < 100; r++)
   {
   for(unsigned int c = 40; c < 100; c++)
     {
     ImageType::IndexType pixelIndex;
     pixelIndex[0] = r;
     pixelIndex[1] = c;

     image->SetPixel(pixelIndex, 50);
     }
   }

} </source>

CMakeLists.txt

<syntaxhighlight lang="cmake"> cmake_minimum_required(VERSION 3.9.5)

project(InvertIntensityImageFilter)

find_package(ITK REQUIRED) include(${ITK_USE_FILE}) if (ITKVtkGlue_LOADED)

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

else()

 find_package(ItkVtkGlue REQUIRED)
 include(${ItkVtkGlue_USE_FILE})
 set(Glue ItkVtkGlue)

endif()

add_executable(InvertIntensityImageFilter MACOSX_BUNDLE InvertIntensityImageFilter.cxx) target_link_libraries(InvertIntensityImageFilter

 ${Glue}  ${VTK_LIBRARIES} ${ITK_LIBRARIES})

</syntaxhighlight>

Download and Build InvertIntensityImageFilter

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

cd InvertIntensityImageFilter/build 

• If ITK is installed:

cmake ..

• If ITK is not installed but compiled on your system, you will need to specify the path to your ITK build:

cmake -DITK_DIR:PATH=/home/me/itk_build ..

Build the project,

make

and run it:

./InvertIntensityImageFilter

WINDOWS USERS PLEASE NOTE: Be sure to add the VTK and ITK bin directories to your path. This will resolve the VTK and ITK dll's at run time.

Building All of the Examples

Many of the examples in the ITK Wiki Examples Collection require VTK. You can build all of the the examples by following these instructions. If you are a new VTK user, you may want to try the Superbuild which will build a proper ITK and VTK.

ItkVtkGlue

ITK >= 4

For examples that use QuickView (which depends on VTK), you must have built ITK with Module_ITKVtkGlue=ON.

ITK < 4

Some of the ITK Examples require VTK to display the images. If you download the entire ITK Wiki Examples Collection, the ItkVtkGlue directory will be included and configured. If you wish to just build a few examples, then you will need to download ItkVtkGlue and build it. When you run cmake it will ask you to specify the location of the ItkVtkGlue binary directory.