ITK/Examples/Developer/MultiThreadedImageFilter: Difference between revisions

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(Created page with "This example demonstrates how to write a filter which uses multiple threads. ==MultiThreadedImageFilterExample.cxx== <source lang="cpp"> #include "itkImage.h" #include "itkImage...")
 
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Line 11: Line 11:
template <typename TImage>
template <typename TImage>
static void CreateImage(TImage* const image);
static void CreateImage(TImage* const image);
template <typename TImage>
static void OutputImage(TImage* const image);


int main(int, char*[])
int main(int, char*[])
Line 24: Line 27:
   FilterType::Pointer filter = FilterType::New();
   FilterType::Pointer filter = FilterType::New();
   filter->SetInput(image);
   filter->SetInput(image);
   filter->SetNumberOfThreads(3);
   // filter->SetNumberOfThreads(3); // There is no need to specify this, it is automatically determined
   filter->Update();
   filter->Update();


   itk::Index<2> cornerPixel = image->GetLargestPossibleRegion().GetIndex();
   std::cout << "Image after filter: " << std::endl;
  OutputImage(image.GetPointer());


  // The output here is:
   std::cout << "Output: " << std::endl;
  // 0
   OutputImage(filter->GetOutput());
  // 3
  // That is, the filter changed the pixel, but the input remained unchagned.
   std::cout << image->GetPixel(cornerPixel) << std::endl;
   std::cout << filter->GetOutput()->GetPixel(cornerPixel) << std::endl;


   return EXIT_SUCCESS;
   return EXIT_SUCCESS;
Line 46: Line 46:
   typename TImage::IndexType corner = {{0,0}};
   typename TImage::IndexType corner = {{0,0}};


   unsigned int NumRows = 200;
//   unsigned int NumRows = 200;
   unsigned int NumCols = 300;
//   unsigned int NumCols = 300;
 
  unsigned int NumRows = 3;
  unsigned int NumCols = 2;
   typename TImage::SizeType size = {{NumRows, NumCols}};
   typename TImage::SizeType size = {{NumRows, NumCols}};


Line 56: Line 59:


   image->FillBuffer(0);
   image->FillBuffer(0);
}
template <typename TImage>
void OutputImage(TImage* const image)
{
  itk::ImageRegionConstIterator<TImage> imageIterator(image, image->GetLargestPossibleRegion());
  while(!imageIterator.IsAtEnd())
    {
    std::cout << imageIterator.Get() << std::endl;
    ++imageIterator;
    }
}
}


Line 77: Line 93:
   typedef ImageToImageFilter< TImage, TImage > Superclass;
   typedef ImageToImageFilter< TImage, TImage > Superclass;
   typedef SmartPointer< Self >        Pointer;
   typedef SmartPointer< Self >        Pointer;
  typedef typename Superclass::OutputImageRegionType OutputImageRegionType;


   /** Method for creation through the object factory. */
   /** Method for creation through the object factory. */
Line 88: Line 106:
   ~MultiThreadedImageFilter(){}
   ~MultiThreadedImageFilter(){}


  /** Does the real work. */
   virtual void ThreadedGenerateData(const OutputImageRegionType &,
   virtual void GenerateData();
                                    ThreadIdType);


private:
private:
Line 124: Line 142:
template< class TImage>
template< class TImage>
void MultiThreadedImageFilter< TImage>
void MultiThreadedImageFilter< TImage>
::GenerateData()
::ThreadedGenerateData(const OutputImageRegionType & region, ThreadIdType threadId)
{
{
  std::cout << "Thread " << threadId << " given region: " << region << std::endl;
   typename TImage::ConstPointer input = this->GetInput();
   typename TImage::ConstPointer input = this->GetInput();
   typename TImage::Pointer output = this->GetOutput();
   typename TImage::Pointer output = this->GetOutput();


   itk::Index<2> cornerPixel = input->GetLargestPossibleRegion().GetIndex();
  ImageAlgorithm::Copy(input.GetPointer(), output.GetPointer(), region,
                      region);
 
   itk::Index<2> cornerPixel = region.GetIndex();
  std::cout << "cornerPixel: " << cornerPixel << std::endl;
   typename TImage::PixelType newValue = 3;
   typename TImage::PixelType newValue = 3;
  this->AllocateOutputs();
  ImageAlgorithm::Copy(input.GetPointer(), output.GetPointer(), output->GetRequestedRegion(),
                      output->GetRequestedRegion() );


   output->SetPixel( cornerPixel, newValue );
   output->SetPixel( cornerPixel, newValue );

Revision as of 15:38, 14 August 2012

This example demonstrates how to write a filter which uses multiple threads.

MultiThreadedImageFilterExample.cxx

<source lang="cpp">

  1. include "itkImage.h"
  2. include "itkImageFileReader.h"
  3. include "itkImageFileWriter.h"
  1. include "MultiThreadedImageFilter.h"

template <typename TImage> static void CreateImage(TImage* const image);

template <typename TImage> static void OutputImage(TImage* const image);

int main(int, char*[]) {

 // Setup types
 typedef itk::Image<int, 2>   ImageType;
 typedef itk::MultiThreadedImageFilter<ImageType>  FilterType;
 ImageType::Pointer image = ImageType::New();
 CreateImage(image.GetPointer());
 // Create and the filter
 FilterType::Pointer filter = FilterType::New();
 filter->SetInput(image);
 // filter->SetNumberOfThreads(3); // There is no need to specify this, it is automatically determined
 filter->Update();
 std::cout << "Image after filter: " << std::endl;
 OutputImage(image.GetPointer());
 std::cout << "Output: " << std::endl;
 OutputImage(filter->GetOutput());
 return EXIT_SUCCESS;

}


template <typename TImage> void CreateImage(TImage* const image) {

 // Create an image with 2 connected components
 typename TImage::IndexType corner = Template:0,0;

// unsigned int NumRows = 200; // unsigned int NumCols = 300;

 unsigned int NumRows = 3;
 unsigned int NumCols = 2;
 typename TImage::SizeType size = Template:NumRows, NumCols;
 typename TImage::RegionType region(corner, size);
 image->SetRegions(region);
 image->Allocate();
 image->FillBuffer(0);

}

template <typename TImage> void OutputImage(TImage* const image) {

 itk::ImageRegionConstIterator<TImage> imageIterator(image, image->GetLargestPossibleRegion());
 while(!imageIterator.IsAtEnd())
   {
   std::cout << imageIterator.Get() << std::endl;
   ++imageIterator;
   }

}

</source>

MultiThreadedImageFilter.h

<source lang="cpp">

  1. ifndef __itkImageFilter_h
  2. define __itkImageFilter_h
  1. include "itkImageToImageFilter.h"

namespace itk { template< class TImage> class MultiThreadedImageFilter : public ImageToImageFilter< TImage, TImage > { public:

 /** Standard class typedefs. */
 typedef MultiThreadedImageFilter             Self;
 typedef ImageToImageFilter< TImage, TImage > Superclass;
 typedef SmartPointer< Self >        Pointer;
 typedef typename Superclass::OutputImageRegionType OutputImageRegionType;
 /** Method for creation through the object factory. */
 itkNewMacro(Self);
 /** Run-time type information (and related methods). */
 itkTypeMacro(ImageFilter, ImageToImageFilter);

protected:

 MultiThreadedImageFilter(){}
 ~MultiThreadedImageFilter(){}
 virtual void ThreadedGenerateData(const OutputImageRegionType &,
                                   ThreadIdType);

private:

 MultiThreadedImageFilter(const Self &); //purposely not implemented
 void operator=(const Self &);  //purposely not implemented

}; } //namespace ITK


  1. ifndef ITK_MANUAL_INSTANTIATION
  2. include "MultiThreadedImageFilter.hxx"
  3. endif


  1. endif // __itkMultiThreadedImageFilter_h

</source>

MultiThreadedImageFilter.hxx

<source lang="cpp">

  1. ifndef __itkMultiThreadedImageFilter_hxx
  2. define __itkMultiThreadedImageFilter_hxx
  1. include "MultiThreadedImageFilter.h"
  1. include "itkObjectFactory.h"
  2. include "itkImageRegionIterator.h"
  3. include "itkImageRegionConstIterator.h"

namespace itk {

template< class TImage> void MultiThreadedImageFilter< TImage>

ThreadedGenerateData(const OutputImageRegionType & region, ThreadIdType threadId)

{

 std::cout << "Thread " << threadId << " given region: " << region << std::endl;
 typename TImage::ConstPointer input = this->GetInput();
 typename TImage::Pointer output = this->GetOutput();
 ImageAlgorithm::Copy(input.GetPointer(), output.GetPointer(), region,
                      region);
 itk::Index<2> cornerPixel = region.GetIndex();
 std::cout << "cornerPixel: " << cornerPixel << std::endl;
 typename TImage::PixelType newValue = 3;
 output->SetPixel( cornerPixel, newValue );

}

}// end namespace


  1. endif

</source>

CMakeLists.txt

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

project(MultiThreadedImageFilter)

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

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

endif()

add_executable(MultiThreadedImageFilter MACOSX_BUNDLE MultiThreadedImageFilter.cxx)

if( "${ITK_VERSION_MAJOR}" LESS 4 )

 target_link_libraries(MultiThreadedImageFilter ITKReview ${ITK_LIBRARIES})

else( "${ITK_VERSION_MAJOR}" LESS 4 )

 target_link_libraries(MultiThreadedImageFilter ${ITK_LIBRARIES})

endif( "${ITK_VERSION_MAJOR}" LESS 4 )

</syntaxhighlight>

Download and Build MultiThreadedImageFilter

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

cd MultiThreadedImageFilter/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:

./MultiThreadedImageFilter

WINDOWS USERS PLEASE NOTE: Be sure to add the ITK bin directory to your path. This will resolve the 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.