City governments can use PHADE technology to send alerts to distracted pedestrians when cars are approaching. (Purdue University)

A Purdue University Ph.D. student co-developed PHADE, a technology that allows public cameras to send personalized messages to people without compromising their privacy. The system uses motion patterns as the address code for communication. The smartphones then locally make their own decisions on whether to accept a message.

PHADE protects privacy in two key ways – it keeps the users’ personal sensing data within their smartphones, and it transforms the raw features of the data to blur partial details. The creators named the system PHADE because the blurring process “fades” out people’s motion details.