We present HiLight, a new form of screen-camera communication without the need of any coded images ( e.g.  barcodes) for off-the-shelf smart devices. HiLight hides information underlying any images shown on a LED or an OLED screen, so that camera-equipped smart devices can fetch the information by turning their cameras to the screen. HiLight achieves this by leveraging the orthogonal transparency (alpha) channel, a well-known concept in computer graphics, to embed bits into pixel translucency changes without the need of modifying pixel color (RGB) values. We demonstrated HiLight's feasibility using smartphones. By offering an unobtrusive, flexible, and lightweight communication channel between screens and cameras, HiLight opens up opportunities for new HCI and context-aware applications to emerge,  e.g.  smart glass communicates with screens for additional personalized information to realize augmented reality.
['Tianxing Li', 'Chuankai An', 'Andrew T. Campbell', 'Xia Zhou']
HiLight: hiding bits in pixel translucency changes