The document provides an overview of the ITK (Insight Toolkit) architecture including its use of generic programming, data pipelines, multi-threading and streaming for image processing. It discusses key ITK concepts such as smart pointers, const correctness, image creation and I/O, exceptions, events and observers, and GUI communication.

1. ITK Architecture Kitware Inc.

3. Generic Programming Example: STL Standard Template Library Abstraction of Types and Behaviors std ::vector< T > std ::vector< int > std ::vector< double > std ::vector< char * > std ::vector< Point > std ::vector< Image >

4. itk::Image itk ::Image< PixelType , Dimension > itk ::Image< char , 2 > itk ::Image< char , 3 > itk ::Image< char , 4 > itk ::Image< float , 2 > itk ::Image< RGB , 3 > itk ::Image< unsigned short , 2 > itk ::Image< itk :: Vector< float,2 > , 2 >

5. namespaces Avoid naming collisions itk :: itk ::Statistics:: itk ::fem:: itk ::fem:: itpack itk ::bio

6. Your favorite keyword typedef typedef itk ::Image< char , 2 > ImageType typedef itk ::ImageFilter< ImageType , ImageType > FilterType otherwise... itk ::ImageFilter< Image< char , 2 > , Image< char , 2 > > FilterType

7. Smart Pointers Object counter=0 counter=1 counter=2 counter=3 Self - Delete Smart Pointer Smart Pointer Smart Pointer

8. SmartPointers typedef itk ::Image< char , 2 > ImageType typedef itk ::ImageFilter< ImageType , ImageType > FilterType FilterType:: Pointer filter = FilterType:: New() ; ImageType:: Pointer image = filter-> GetOutput() ; NO NEED FOR filter-> Delete() ; Pointer notation filter-> Update() ;

9. Const Correctness Knowing constancy is Insight. Not knowing constancy leads to disaster. Tao Te Ching , XVI. Lao Tsu

10. Const Smart Pointers typedef itk ::Image< char , 2 > ImageType typedef itk ::ImageFilter< ImageType , ImageType > FilterType FilterType:: Pointer filter = FilterType:: New() ; ImageType:: ConstPointer image = filter-> GetOutput() ; Can only invoke “const” methods image -> GetSpacing () ; Compiler error for “non-const” methods image -> SetSpacing ( spacing ) ;

11. Creating an Image typedef itk ::Image< char , 3 > ImageType ImageType:: Pointer image = ImageType:: New(); ImageType :: SizeType size ; size [ 0 ] = 512; // x direction size [ 1 ] = 512; // y direction size [ 2 ] = 50; // z direction ImageType :: IndexType start ; start [ 0 ] = 0; // x direction start [ 1 ] = 0; // y direction start [ 2 ] = 0; // z direction

12. Creating an Image ImageType :: RegionType region ; region .SetSize( size ); region .SetIndex( start ); image ->SetRegions( region ); image ->Allocate(); image ->FillBuffer( 0 ); ImageType :: SpacingType spacing ; spacing [ 0 ] = 0.83; // x direction spacing [ 1 ] = 0.83; // y direction spacing [ 2 ] = 2.15; // z direction image ->SetSpacing( spacing );

13. Exercise 3

14. Streaming Output Image Filter Processing Large Images Input Image

15. Image Regions LargestPossibleRegion BufferedRegion RequestedRegion

16. Data Pipeline Image Filter Image Filter Image Image Image Filter

17. Simple Image IO Image File ImageFileReader Image Filter Image Image File ImageFileWriter

18. Simple Image IO Loadable Factories CustomImageIO Image File ImageFileReader Image PNGImageIO VTKImageIO DICOMImageIO GIPLImageIO MetaImageIO AnalyzeImageIO

19. Simple Image IO #include “ itkImage.h ” #include “ itkImageFileReader.h ” #include “ itkImageFileWriter.h ” typedef itk :: Image< char , 2 > ImageType; typedef itk :: ImageFileReader< ImageType > ReaderType; typedef itk :: ImageFileWriter< ImageType > WriterType; ReaderType:: Pointer reader = ReaderType:: New(); WriterType:: Pointer writer = WriterType:: New(); reader -> SetFileName( “inputImage.dcm” ) ; // DICOM writer -> SetFileName( “outputImage.hdr” ) ; // Analyze writer -> SetInput( reader -> GetOutput() ) ; writer -> Update() ;

20. Exceptions Error Management ITK Layer Application Layer

21. Exceptions try { filter->Update(); } catch( itk:: ExceptionObject & exp ) { std::cerr << exp << std::endl; }

22. Exercise 4 Image File ImageFileWriter Caster Image File ImageFileReader Filter

23. Events and Observers Itk::Object Itk::Command itk::Command itk::Command itk::Command itk::Command Event Event Event Event Event

24. Events and Observers Common Events AnyEvent() StartEvent() EndEvent() ProgressEvent() IterationEvent()

25. Events and Observers Execute() Itk::Object Itk::ProcessObject Itk::FilterXY Itk::Command MyCommand AddObserver( ) AnyEvent MyEvent

26. Events and Observers Itk::Object Itk::ProcessObject Itk::FilterXY Itk::Command Itk::SimpleMemberCommand AddObserver( ) MyClass MethodX() AnyEvent MyEvent

27. Exercise 5 Execute() ProgressEvent() StartEvent() EndEvent() Image File ImageFileReader Filter ImageFileWriter Image File CommandObserver

28. GUI Communication ITK Layer GUI Layer Widget FilterX Callback Command FilterX Widget Observer

29. Enjoy ITK !