ImageBeacon: Broadcasting Color Images over Connectionless Bluetooth LE Packets

This paper describes the first `image beacon' system that is capable of broadcasting color images over a very long period (years, as opposed to days or weeks) using a set of cheap, low-power, memory-constrained Bluetooth Low Energy (BLE) beacon devices. We design an image processing pipeline that takes into account the background and foreground information of an image and then applies an adaptive encoding method which priorities more important regions of an image during encoding, in order to achieve the best quality image under a very strict size limit. We test our system with different types of RGB images that contain indoor and outdoor objects, buildings, and road signs. We empirically determine the tradeoffs between the system lifetime and the quality of broadcasted images, and determine an optimal set of parameters for our system, under user-specified constraints such as the number of available beacon devices, maximum latency, and life expectancy. We develop a smartphone application that takes an image and user requirements as inputs, shows previews of different quality output images, writes the encoded image into a set of beacons, and reads the broadcasted image back. Our evaluation shows that a set of 2-3 beacons is capable of broadcasting high-quality images (70% structurally similar to original images) for a year-long continuous broadcasting, and both the lifetime and the image quality improve when more beacons are used.