PaperUI is a human-information interface concept that advocates using paper as displays and using mobile devices, such as camera phones or camera pens, as traditional computer-mice. When emphasizing technical efforts, some researchers like to refer the PaperUI related underlying work as interactive paper system. We prefer the term PaperUI for emphasizing the final goal, narrowing the discussion focus, and avoiding terminology confusion between interactive paper system and interactive paper computer [40]. PaperUI combines the merits of paper and the mobile devices, in that users can comfortably read and flexibly arrange document content on paper, and access digital functions related to the document via the mobile computing devices. This concept aims at novel interface technology to seamlessly bridge the gap between paper and computers for better user experience in handling documents. Compared with traditional laptops and tablet PCs, devices involved in the PaperUI concept are more light-weight, compact, energy efficient, and widely adopted. Therefore, we believe this interface vision can make computation more convenient to access for general public.