NAMIC Wiki:DTI:ITK

Test for the Diffusion Tensor pixel type

The following code is a typical test file for the functionalities implemented in the DiffusionTensorPixel type. It also exercises the use of this pixel type in an itk::Image instantiation.

 #if defined(_MSC_VER)
 #pragma warning ( disable : 4786 )
 #endif
 
 #include <iostream>
 
 #include "itkDiffusionTensorPixel.h"
 #include "itkImage.h"
 #include "itkImageRegionIterator.h"
 
 int itkDiffusionTensorPixelTest(int, char* [] )
 {
   int i, j;
 
   // Test it all
 
   float val[6] = {1.8, 0.2, 0.5, 3.4, 2.0, 1.2};
   itk::DiffusionTensorPixel<float> pixel(val);
   unsigned char pixelInit0[6] = {255, 255, 255};
   unsigned char pixelInit1[6] = {255, 255, 244};
   itk::DiffusionTensorPixel<unsigned char> pixelArray[2];
   pixelArray[0] = pixelInit0;
   pixelArray[1] = pixelInit1;
 
   std::cout << "sizeof(pixel) = " << sizeof (pixel) << std::endl;
   if (sizeof(pixel) != 6 * sizeof(itk::DiffusionTensorPixel<float>::ComponentType))
     {
     std::cerr << "ERROR: sizeof(pixel) == " << sizeof(pixel) << " but is should be " << 6 * sizeof(itk::DiffusionTensorPixel<float>::ComponentType) << std::endl;
     return 1;
     }
   std::cout << "pixel.GetNumberOfComponents = " << pixel.GetNumberOfComponents() << std::endl;
   std::cout << "pixel.GetNthComponent()" << std::endl;
   for (i = 0; i < pixel.GetNumberOfComponents(); i++)
     {
     std::cout << "\tpixel[" << i << "] = " << pixel.GetNthComponent(i) << std::endl;
     }
 
   pixel(0,0) = 11.0;
   pixel(0,1) = 21.0;
   pixel(0,2) = 15.0;
   pixel(1,0) = 11.0;
   pixel(1,1) = 31.0;
   pixel(1,2) = 10.0;
   pixel(2,0) = 11.0; // these three last element will overwrite its symmetric counterparts
   pixel(2,1) = 41.0;
   pixel(2,2) = 14.0;
 
   std::cout << "testing the pixel(i,j) APID" << std::endl;
   for (i = 0; i < pixel.GetNumberOfComponents(); i++)
     {
     std::cout << "\tpixel[" << i << "] = " << pixel.GetNthComponent(i) << std::endl;
     }
 
   std::cout << "pixel[0] = 111; pixel[1] = 222; pixel[2] = 333;" << std::endl;
   std::cout << "pixel[3] = 444; pixel[4] = 555; pixel[5] = 666;" << std::endl;
 
   pixel[0] = 111; pixel[1] = 222; pixel[2] = 333;
   pixel[3] = 444; pixel[4] = 555; pixel[5] = 666;
 
   for (i = 0; i < pixel.GetNumberOfComponents(); i++)
     {
     std::cout << "\tpixel[" << i << "] = " << pixel.GetNthComponent(i) << std::endl;
     }
 
   std::cout << "std::cout << pixel << std::endl;" << std::endl;
   std::cout << "\t" << pixel << std::endl;
 
   for (j = 0; j < 2; j++)
     {
     std::cout << "pixelArray["<< j << "].GetNumberOfComponents = " << pixelArray[j].GetNumberOfComponents() << std::endl;
     std::cout << "pixelArray[" << j << "].GetNthComponent()" << std::endl;
     for (i = 0; i < pixelArray[j].GetNumberOfComponents(); i++)
       {
       std::cout << "\tpixelArray[" << j << "].GetNthComponent(" << i << ") = " << static_cast<int>(pixelArray[j].GetNthComponent(i)) << std::endl;
       }
     }
 
   std::cout << "Testing arithmetic methods" << std::endl;
   itk::DiffusionTensorPixel< float > pa;
   itk::DiffusionTensorPixel< float > pb;
 
   pa[0] = 1.25;
   pa[1] = 3.25;
   pa[2] = 5.25;
   pa[3] = 1.25;
   pa[4] = 3.25;
   pa[5] = 5.25;
 
   pb[0] = 1.55;
   pb[1] = 3.55;
   pb[2] = 5.55;
   pb[3] = 1.55;
   pb[4] = 3.55;
   pb[5] = 5.55;
 
   itk::DiffusionTensorPixel< float > pc;
 
   pc = pa + pb;
   std::cout << "addition = " << pc << std::endl;
 
   pc = pa - pb;
   std::cout << "subtraction = " << pc << std::endl;
 
   pc += pb;
   std::cout << "in-place addition = " << pc << std::endl;
 
   pc -= pb;
   std::cout << "in-place subtraction = " << pc << std::endl;
 
   pc = pa * 3.2;
   std::cout << "product by scalar = " << pc << std::endl;
 
 
 
 
   /** Create an Image of tensors  */
   typedef itk::DiffusionTensorPixel< float >   PixelType;
   typedef itk::Image< PixelType, 3 >           ImageType;
 
   ImageType::Pointer dti = ImageType::New();
 
   ImageType::SizeType  size;
   ImageType::IndexType start;
   ImageType::RegionType region;
 
   region.SetIndex( start );
   region.SetSize( size );
 
   dti->SetRegions( region );
   dti->Allocate();
 
   ImageType::SpacingType spacing;
   spacing[0] = 0.5;
   spacing[1] = 0.5;
   spacing[2] = 1.5;
 
   ImageType::PointType origin;
   origin[0] = 25.5;
   origin[1] = 25.5;
   origin[2] = 27.5;
 
   dti->SetOrigin( origin );
   dti->SetSpacing( spacing );
 
   PixelType tensor;
 
   tensor[0] = 1.2;
   tensor[1] = 2.2;
   tensor[2] = 3.2;
   tensor[3] = 4.2;
   tensor[4] = 5.2;
   tensor[5] = 6.2;
 
   dti->FillBuffer( tensor );
 
   typedef itk::ImageRegionIterator< ImageType > IteratorType;
 
   IteratorType it( dti, region );
   it.GoToBegin();
 
   while( !it.IsAtEnd() )
     {
     it.Set( tensor );
     ++it;
     }
 
 
   return EXIT_SUCCESS;
 }