[Insight-users] Indexing itk::Image

[motes motes]

As I understand pixels in an image is located using a indexType:

// 2D case:
IndexType idx;
idx[0] = 3;
idx[1] = 4;

ImageType::Pointer image = reader->GetOutPut(); // from some reader.
image->GetPixel(idx);

The above example get the value of the pixel at location (3,4) in the image.

But in the itk::Image.h file it says:

 *
 * The data in an image is arranged in a 1D array as [][][][slice][row][col]
 * with the column index varying most rapidly.  The Index type reverses
 * the order so that with Index[0] = col, Index[1] = row, Index[2] = slice,
 * ...

I don't understand this notation:

     [][][][slice][row][col]

does it mean that if I do:

image[0];

I get the first whole column of the image? And what does the prefix
[][][]...stand for?






//Example:
In the BSplineDeformableTransform images m_WrappedImage and
m_CoefficientImage are used like this:

  PixelType * dataPointer = const_cast<PixelType *>((
m_InputParametersPointer->data_block() ));
  unsigned int numberOfPixels = m_GridRegion.GetNumberOfPixels();

  for ( unsigned int j = 0; j < SpaceDimension; j++ ) {
    m_WrappedImage[j]->GetPixelContainer()->SetImportPointer(
dataPointer, numberOfPixels );
    dataPointer += numberOfPixels;
    m_CoefficientImage[j] = m_WrappedImage[j];
  }

To my understanding this first sets the column of m_WrappedImage to
the first half of the parameters and then copies that to the
m_CoefficientImage. Next the last half of the parameters are copied to
the row of m_WrappedImage and then copied to m_CoefficientImage. But I
am pretty sure this is not what goes on, what does:

m_CoefficientImage[0]
m_CoefficientImage[1]

actually mean for the 2D case?