Image acquisition apparatus (1) for acquiring images of mailpieces (P), the apparatus comprising a housing (3) inside which the following are placed: a first camera (4) co-operating with a first lighting system (8) emitting light radiation at a certain wavelength suitable for exciting a fluorescent mark to acquire an image of the surface of a mailpiece through a first window (5); a second camera (6) co-operating with a second lighting system (9) emitting light radiation in the visible light domain to acquire an image of the surface of a mailpiece through a second window (7); and means (10) for preventing light interference, which means are concave in shape and are disposed between the first window and the second window, the second lighting system (9) being disposed in the cavity of said means (10) for preventing light interference.