My understanding is that the video signal is fed through with zero processing and without touching the main processor, and the lines are simply overlaid, the lines don't need to know what the camera sees.
This is actually why several people said that the parking lines would never happen before the update that installed them, it was thought that without the video going through the main processor they couldn't do an overlay, turns out they can, but that's a whole different ballgame from trying to send the video to the app.
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The front camera has it's own chip in it running the mobileye software and designed specifically to do all sorts of differentiations. That said, I actually think the different pictures are based on the radar, not the camera.
Other members of this forum have completely taken the car apart and proved what connections go where. There's simply no video feed from the camera.