LAUSR

Visible light communication based on display and camera can simultaneously provide the functionalities of display and invisible information transmission. There are widely potential applications in information broadcasting, stealth advertising, etc. In this paper, a real-time display camera communication system based on LED displays and smartphones is proposed. To solve the rate mismatch problem and the symbol unsynchronization problem between the LED display panel with a relatively high frame rate and the smartphones' camera with a relatively low frame rate, we propose an Alternate Bit-flipping Repeat Coding scheme for adjustable frame rate matching and symbol synchronization with the advantage of eliminating flickers perceivable to human eyes. Fast image processing algorithms are also designed to decrease the computational complexity of extracting information from the captured video frames in real-time. An experimental system was implemented on a 16×16 points LED display panel with a refresh rate of 150 fps and a commercial Android smartphone with an 8 megapixels camera working at 30 fps and a self-developed Android APP. The experimental results show that the real-time LED display camera communication system can achieve a data transmission rate of 30 bps for one LED display point and a maximum distance of 80 cm, and the computational time on the Android smartphone for data receiving is only 11.827 ms.