I don't know the technical details of how it's encoded, but digital radio stations can embed metadata in their signal that the car radio can display. That inclu

I don't know the technical details of how it's encoded, but digital radio stations can embed metadata in their signal that the car radio can display. That includes text, like the station name, and also images, like a logo, that's usually shown next to the station name. I believe it's part of HD Radio: https://en.wikipedia.org/wiki/HD_Radio https://en.wikipedia.org/wiki/HD_Radio.