ITK/Examples/Developer/MultiThreadedImageFilter: Difference between revisions

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This example demonstrates how to write a filter which uses multiple threads.
{{warning|1=The media wiki content on this page is no longer maintained. The examples presented on the https://itk.org/Wiki/*  pages likely require ITK version 4.13 or earlier releases.   In many cases, the examples on this page no longer conform to the best practices for modern ITK versions.}}
 
==MultiThreadedImageFilterExample.cxx==
<source lang="cpp">
#include "itkImage.h"
#include "itkImageFileReader.h"
#include "itkImageFileWriter.h"
 
#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 = {{0,0}};
 
//  unsigned int NumRows = 200;
//   unsigned int NumCols = 300;
 
  unsigned int NumRows = 3;
  unsigned int NumCols = 2;
  typename TImage::SizeType size = {{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">
#ifndef __itkImageFilter_h
#define __itkImageFilter_h
 
#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
 
 
#ifndef ITK_MANUAL_INSTANTIATION
#include "MultiThreadedImageFilter.hxx"
#endif
 
 
#endif // __itkMultiThreadedImageFilter_h
 
</source>
 
==MultiThreadedImageFilter.hxx==
<source lang="cpp">
#ifndef __itkMultiThreadedImageFilter_hxx
#define __itkMultiThreadedImageFilter_hxx
 
#include "MultiThreadedImageFilter.h"
 
#include "itkObjectFactory.h"
#include "itkImageRegionIterator.h"
#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
 
 
#endif
</source>
 
{{ITKCMakeLists|MultiThreadedImageFilter}}

Latest revision as of 18:31, 7 June 2019

Warning: The media wiki content on this page is no longer maintained. The examples presented on the https://itk.org/Wiki/* pages likely require ITK version 4.13 or earlier releases. In many cases, the examples on this page no longer conform to the best practices for modern ITK versions.