HiLight: Hiding Bits in Pixel Translucency Changes

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 im-ages 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 Hi-Light’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 communi-cates with screens for additional personalized information to realize augmented reality