关于二维码的四个纠错等级

There are 4 error correction levels used for QR codes, with each one adding different amounts of “backup” data depending on how much damage the QR code is expected to suffer

in its intended environment, and hence how much error correction may be required:

Level L – up to 7% damage
Level M – up to 15% damage
Level Q – up to 25% damage
Level H – up to 30% damage