Design

A logo in the middle of a QR code lifts scan rates, because a branded code looks deliberate rather than like something a stranger stuck to a lamp post. It also covers data. The trick is understanding exactly how much you can cover before the code stops working. Why it works at all QR codes carry Reed-Solomon error correction: redundant data that lets a reader reconstruct modules it cannot see. That is why a code still scans with a coffee ring on it.