QR codes have error correction that can be set to four levels (http://www.qrcode.com/en/about/error_correction.html http://www.qrcode.com/en/about/error_correct

QR codes have error correction that can be set to four levels (http://www.qrcode.com/en/about/error_correction.html http://www.qrcode.com/en/about/error_correction.html). If you set the level high enough, you can cover parts of the code and it will still be readable.