(photography) Any undesired image appearing at the image plane of an optical system; either a false image of the desired object, or an out-of-focus image of a bright source of light in the field of the optical system.

(computing) A copy of all the contents of a hard drive, used as a backup.

plural of ghost image

(computing) The process of creating a ghost image of all the contents of a hard drive as a backup that may be stored and later retrieved if needed.