FlashLight: Optical communication between mobile phones and interactive tabletops

Mobile phones can be used as mediators between users and interactive tabletops in several scenarios, including authenti-cation and the sharing of information. Existing radio-based methods such as WiFi or Bluetooth offer a high-speed com-munication channel, but have serious limitations regarding the tabletop-phone-human interaction. They are not able to locate mobile phones placed on the surface, often require fairly complex coupling procedures for establishing connec-tions, and are potentially vulnerable to eavesdropping attacks. In this paper, we present a method for establishing a bidirec-tional communication channel between mobile phones and vision-based interactive surfaces utilizing the built-in flash-light and camera of mobile phones and the screen and came-ra of vision-based tabletops. We establish an entirely visual, secure and bidirectional communication channel at a speed superior to previous vision-based approaches, enabling users to establish connections and transfer data to and from inter-active surfaces using ordinary out-of-the-box hardware. ACM Classification: H5.2 [Information interfaces and pre