diff_self: Flipped Difference Image
In muschellij2/extrantsr: Extra Functions to Build on the 'ANTsR' Package

This function flips the image over the left/right axis, then registers the flipped image to the original image and then takes a difference

1	diff_self(img, swapdim = TRUE, verbose = TRUE, reproducible = TRUE, seed = 1)

`img`	Object of class `nifti`, `ANTsR`, or `character`
`swapdim`	Should the image be reoriented to RPI then flipped, registered, then changed back?
`verbose`	Print diagnostic messages
`reproducible`	Sets the seed and `Sys.setenv(ITK_GLOBAL_DEFAULT_NUMBER_OF_THREADS = 1)`. See https://github.com/ANTsX/ANTs/wiki/antsRegistration-reproducibility-issues for discussion.
`seed`	will execute `Sys.setenv(ANTS_RANDOM_SEED = seed)` before running to attempt a more reproducible result. If `NULL`, will not set anything, but `reproducible` must be `FALSE`.