Embodiments herein observe the backing of the document handler to determine if a document was left on the platen and would block the scan head from scanning the documents as they are moved by the document handler. An embodiment herein comprises a transparent platen and a document handler on a first side of the platen. The document handler has a backing, and the backing is adapted to move media within the document handler. A scan head is positioned on a second side of the platen. The scan head remains stationary when scanning the media being moved by the document handler and the scan head moves when scanning media on the platen. The backing of the document handler has a surface that is distinguishable from the media such that the scan head can detect whether the media is on the platen and would block the scan head from scanning the media being moved by the document handler.