Image extension are not "detected" from VTK

[skinkie]

The main window selects its extentions at this point.

https://github.com/Kitware/TeleSculptor/blob/master/gui/MainWindow.cxx#L141

I have modified the source code to show what VTK exports.

  // Get registered readers
  vtkNew<vtkImageReader2Collection> readers;
  vtkImageReader2Factory::GetRegisteredReaders(readers);

  // Extract extensions for each reader
  readers->InitTraversal();
  while (auto const reader = readers->GetNextItem())
  {
      std::cout << reader->GetFileExtensions() << std::endl;
  }

Which results in:

.png
.pnm .pgm .ppm
.tif .tiff
.bmp
.slc
.hdr .pic
.jpeg .jpg
.MR .CT
.mhd .mha

Still:

While: