Error Correction

Error correction is a mechanism that allows the original data to be restored even when parts of a QR code are dirty or damaged. It is implemented using a mathematical algorithm called Reed-Solomon error correction.

There are four error correction levels: L (recovers about 7%), M (about 15%), Q (about 25%), and H (about 30%). Higher levels provide greater recovery capability but reduce the amount of data that can be stored. Level H is commonly chosen for design QR codes with a logo overlaid in the center.