How QR Code Error Correction Lets Logos Sit at the Center Without Breaking Scans

QR codes remain scannable even when partially covered because they embed redundant data calculated using Reed-Solomon error correction. This system operates at four levels — L, M, Q, and H — allowing up to 30% of a code's modules to be damaged or obscured while still being reconstructed by a reader. Placing a logo at the center works as long as the masked area stays within that correction threshold, which is why designers are advised to use the highest correction level (H) and limit the logo to roughly the central fifth of the code. Critical mistakes include oversized logos that exceed the correction limit and covering the three corner squares, known as 'eyes,' which are essential for reader alignment and cannot be compensated by error correction. Testing the final design on an actual phone at its intended print size is recommended to confirm scannability.