Demonstration of a covert camera-screen communication system

We design and demonstrate a covert camera-screen communication (CSC) system. It embeds data in display images and retrieves information using a commercial camera. Pixels or blocks of pixels are modulated by a spatial visual modulation scheme. To ensure reliable data transmission while incurring little effect on the screen-viewing experience, two-dimensional Gaussian distribution of the intensity is applied. Also the synchronization anchors are added to each data frame to tackle the unstable frame rate issue of the camera. The system throughput and bit error rate (BER) performance under different imperfect factors are experimentally tested. Results show that the proposed system achieves an average throughput of 16.67 kbps at a regular screen refresh rate 60Hz and remains imperceivable to an observer. The throughput is comparable to that by existing works relying on a rate 120Hz.