A Lumière Brothers "Autochrome" of a Nieuport 23 C.1 fighter The Nieuport 17 had a centered Vickers machine gun, the 23 as here was offset.  Other details were minor.  May, 1917.
Two other Autochrome images of camouflaged Nieuports also exist; a Nieuport 11 photographed in April of 1916 and an earlier built Nieuport 10 image taken at a Belgian flying school.
Nieuport
Nieuport