Reverse the logic for flipping TIFF images
The TIFF reader was flipping the image if the origin was not in the top-left, but in my testing and reading the documentation vtkImageData's origin is in the bottom-left. Comparing a number of TIFF images to those read by ImageJ, Gwenview, and system previews to get a match in VTK tests or Tomviz requires flipping the logic.