Once digital images of cultural and heritage material are digitized and placed online, how can we tell if they are copied, disseminated, and reused? This poster explores Reverse Image Lookup (RIL) technologies — usually used to identify unlicensed reuse of commercial photography — to help in assessing the impact of digitized content. We report on a pilot study which tracked a sample of images from The National Gallery, London, to establish where they were reused on other webpages. In doing so, we assessed the current methods available for applying RIL, establishing how useful it can be to the cultural and heritage sectors.