Digital image processing in led visible light communications using mobile phone camera

Visible light communication (VLC) has recently emerged to become a promising wireless communication technology. It is attractive if the mobile phone camera can be used as the visible light communication receiver. In this paper, a feasible digital image processing scheme for the application of VLC using mobile phone camera as receiver is proposed. The camera for the signal reception captures the information in the form of light and dark stripes which are then decoded by the computer in the MATLAB and the received message is displayed. In order to mitigate the interferences of the LED facula and extend the VLC transmission distance, we utilize a lot of methods of digital image processing, which include grayscale conversion, removal of low grayscale and LED facula, histogram equalization and high pass filter. Through the image processing, the light and dark stripes are clearer and easier to be decoded. Then a second-order polynomial fitting is used to define the threshold and the binary result is obtained. The experimental results show that the robustness of system is obviously improved and the VLC system can resist interferences and background noise.