[Insight-users] How to write the Image after Iterator operation

[Fucang Jia]

Hello, everyone,

I want to threshold a gray image using Otsu method. But I can not write the 
binaried image. I have not understand the iterator, could anyone explain 
what is wrong? Here is the code:


  typedef  unsigned char  PixelType;
  PixelType threshold;

  typedef itk::Image< PixelType,  2 >   		 ImageType;
  typedef itk::OtsuThresholdImageCalculator< ImageType > CalculatorType;
  typedef itk::ImageFileReader< ImageType >  		 ReaderType;
  typedef itk::ImageFileWriter< ImageType >  		 WriterType;
  typedef itk::ImageRegionIterator< ImageType > 	 IteratorType;

  ReaderType::Pointer reader = ReaderType::New();
  CalculatorType::Pointer calculator = CalculatorType::New();
  WriterType::Pointer writer = WriterType::New();
  itk::MetaImageIO::Pointer metaWriter = itk::MetaImageIO::New();

  reader->SetFileName( argv[1] );
  reader->Update();

  calculator->SetImage(reader->GetOutput());
  calculator->Compute();
  threshold = calculator->GetThreshold();

  ImageType::Pointer image=reader->GetOutput();
  ImageType::RegionType region = image->GetBufferedRegion();

  IteratorType it(image,region);
  it.GoToBegin();

  while(!it.IsAtEnd())
   {
	   if(it.Value()<threshold)
		   it.Set(0);
	   else
		   it.Set(255);
	   ++it;
   }

  writer->SetImageIO(metaWriter);
  writer->SetFileName(argv[2]);
  writer->SetInput(it);
  writer->Write();

==========================================
/data2/itkcvs/Insight/Examples/Filtering/OtsuThreshold.cxx: In
   function `int main(int, char**)':
/data2/itkcvs/Insight/Examples/Filtering/OtsuThreshold.cxx:57: no
   matching function for call to `itk::ImageFileWriter<main(int,
   char**)::ImageType>::SetInput(main(int, char**)::IteratorType&)'
/data2/itkcvs/Insight/Code/IO/itkImageFileWriter.txx:51: candidates are: 
void
   itk::ImageFileWriter<TInputImage>::SetInput(const TInputImage*) [with
   TInputImage = main(int, char**)::ImageType]
make[3]: *** [BinaryThresholdImageFilter.o] Error 1
make[2]: *** [default_target] Error 2
make[1]: *** [default_target_Filtering] Error 2
make: *** [default_target] Error 2

I looked some code,  the error occurred on line "writer->SetInput(it);", but 
I do not know how to correct this line.

Thanks !

Fucang





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