pub fn align_stack(
images: &[Gray],
reference: usize,
options: &Options,
) -> Result<Vec<Shift>, Error>Expand description
How far each exposure has to move to sit on images[reference], measured
between adjacent exposures and accumulated: one percentile fits two
neighbours well and the ends of a bracket badly.
So images has to be in exposure order, which is not always the order the
camera wrote the files in.