preexposure

or pre-ex·po·sure

[ pree-ik-spoh-zher ]
/ ˌpri ɪkˈspoʊ ʒər /

noun

exposure beforehand.
Photography. the exposing of a film to even light, before photographing a subject, to increase its sensitivity.

Origin of preexposure

First recorded in 1935–40; pre- + exposure