QR Code Generation and Logo QR Design

How a QR Code Works

A QR code stores data in a two-dimensional matrix with built-in error correction, so a partially damaged code can still be decoded. The three large squares in the corners let a reader find and orient the code from any angle.

Error Correction Levels

Four levels exist — L, M, Q and H — recovering roughly 7%, 15%, 25% and 30% of the data respectively. Higher correction means a denser code that needs more space. Use H when embedding a logo, Q where the surface may be scuffed.

Static and Dynamic

Static: the destination is inside the code and permanent. No dependency on any service.

Dynamic: the code points to a redirect, so the destination can change later and scans can be counted — at the cost of depending on that service.

This decision must be made before printing; it cannot be reversed afterwards.

Logo Integration

A logo can sit at the centre with error correction H, covering no more than about 20% of the code area. Beyond that the recoverable data margin is exhausted and scanning becomes unreliable. Logo codes are always tested at actual print size.

Print Criteria

• Minimum 15 mm edge length on labels; 20 mm is safer
• Quiet zone of at least 4 modules on all sides
• Dark code on a light background — inverted contrast fails on some readers
• Matte finish; gloss lamination reflects camera flash
• Shorter URLs produce sparser codes that read more easily when small

Testing

Print at actual size and test with at least three phones of different make and age, in both daylight and store lighting. Enlarged on-screen previews never represent real print.