LuxBoard: Ambient Light Manipulation for Contactless Text Entry on Mobile Devices

In this paper, we present a proof-of-concept for text entry technique that requires no direct contact with the mobile device and relies exclusively on built-in light sensor utilization. Simple in-air gestures, performed above the smartphone screen, alter the current level of ambient lighting. This allows adjusting the keyboard cursor position based on the sensor readings. The idea of this work is in accordance with the Around-Device Interaction (ADI) concept, currently attracting a lot of attention in the Human-Computer Interaction field. The proposed solution successfully augments an input area of a mobile device without the use of sophisticated peripherals. Two different methods can be used to select the target character, depending on how the keyboard cursor is operated. While manual control requires continuous hand gestures to directly adjust the cursor position, automatic control is based on stopping the cursor along its predefined route. In the conducted experiment, 32 participants utilized the touchless interaction technique for both text entry methods on their own smartphone devices. The outcomes of this empirical research are reported, with a special emphasis on text entry speed, total error rate, usability attributes, and perceived workload.