Offline screen-to-camera transfer. The laptop shows a stream of QR frames and the phone reads them with its camera. No network is used for the data itself.
Choose a photo.
Tips: turn screen brightness up, hold the phone 25–40 cm away, keep the QR filling about ⅔ of the camera frame. The stream loops, so missed frames come round again. If the phone stalls, lower frames/sec or bytes/frame.
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Point the camera at the laptop screen.