An image intensifier is provided in which a thin film (090) is arranged between an output surface of the electron multiplier (040) and the phosphorous screen. The thin film is a semi-conductor or insulator with a crystalline structure comprising a band gap equal or larger than 1 eV, wherein the crystalline structure has a carrier diffusion length equal or larger than 50% of the thickness of the thin film. In addition, the thin film has an anode directed surface which has a negative electron affinity. By way of provisioning a thin film of the above type in the image intensifier, an improvement in mean transfer function of the overall image intensifier is obtained.