[Insight-users] Get the number of components per pixel without reading image

[David Doria]

On Wed, Nov 28, 2012 at 5:09 PM, Bill Lorensen <bill.lorensen at gmail.com> wrote:
> Something like this:
>       typedef itk::Image<unsigned char, 3> ImageType;
>       itk::ImageFileReader<ImageType>::Pointer imageReader =
>         itk::ImageFileReader<ImageType>::New();
>       imageReader->SetFileName(fileName.c_str());
>       imageReader->UpdateOutputInformation();
>
>       pixelType = imageReader->GetImageIO()->GetPixelType();
>       componentType = imageReader->GetImageIO()->GetComponentType();

Ah, that is good to know. But you had to know the "3" there ahead of
time, right?

I actually just found ImageIOBase::GetNumberOfComponents() that does
exactly what I was looking for:

  itk::ImageIOBase::Pointer imageIO =
        itk::ImageIOFactory::CreateImageIO(
            filename.c_str(), itk::ImageIOFactory::ReadMode);
  unsigned int numComponents = imageIO->GetNumberOfComponents();

(I thought the Doxygen functions were sorted alphabetically, so I
looked near the GetNumberOfDimensions() function here:
http://www.itk.org/Insight/Doxygen/html/classitk_1_1ImageIOBase.html#pub-methods

but I guess they are not, because if you look down the page further it
is indeed there.)

Is there any benefit of using one of these techniques over the other?

David