[Insight-users] Problems with casting image types

[kumis]

Hi everyone,
I'm trying to do some labeling operations on an DICOM CT image. To do this I
need (I suppose I need) cast the DICOM signed short pixel format to unsigned
char. I want perform this operation after initial thresholding ( the
threshold operation is working on signed short type) but I found a strange
problem here. When I use the CastImageFilter to convert singed short to
unsigned char the output image is completly dark/empty. Could You give me
some advice how to deal with this problem? You can find the code below:


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

int main( int argc, char* argv[] ){

	typedef itk::ImageFileReader<ImageType> ImageFileReaderType;
	ImageFileReaderType::Pointer imageReader = ImageFileReaderType::New();
	imageReader->SetFileName(argv[1]);
	typedef itk::GDCMImageIO ImageIOType;
	ImageIOType::Pointer gdcmIO = ImageIOType::New();
	imageReader->SetImageIO(gdcmIO);


	int lowerThreshold = atoi(argv[2]);
	int upperThreshold = atoi(argv[3]);

	if(lowerThreshold>upperThreshold){
		std::cout<<"incorrect threshold values"<<"\n";
		return EXIT_FAILURE;
	}
	
	typedef itk::BinaryThresholdImageFilter<ImageType,ImageType>
ThresholdImageFilterType;
 	ThresholdImageFilterType::Pointer thresholdFilter =
ThresholdImageFilterType::New();
	thresholdFilter->SetInput(imageReader->GetOutput());
	thresholdFilter->SetLowerThreshold(lowerThreshold);
	thresholdFilter->SetUpperThreshold(upperThreshold);
	thresholdFilter->SetInsideValue(1);
	thresholdFilter->SetOutsideValue(0);
	thresholdFilter->Update();

	typedef itk::CastImageFilter<ImageType,UCImageType>
CastImageFilterSS2UCType;
	CastImageFilterSS2UCType::Pointer castImageFilterSS2UC =
CastImageFilterSS2UCType::New();
	castImageFilterSS2UC->SetInput(thresholdFilter->GetOutput());
        
        QuickView viewer;
	viewer.AddImage(imageReader->GetOutput());
	viewer.AddImage(thresholdFilter->GetOutput());
	viewer.AddImage(castImageFilterSS2UC->GetOutput());
	viewer.Visualize();
	
	return EXIT_SUCCESS;
}


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