LoRa fits the low power and its also long range. I have never sent images over it but for sure its possible but unreliable, as its very low bandwith.
I would do some kind of computer vision to identify people, or count them and send that data instead, those operations should be easy on a microcontroller.
I would do some kind of computer vision to identify people, or count them and send that data instead, those operations should be easy on a microcontroller.