Matrix symbology
Aztec
Aztec Code is a two-dimensional symbology whose defining feature is that it requires no quiet zone at all, which makes it the most space-efficient option where the surrounding clear space is the binding constraint. Its finder pattern is a bullseye at the centre rather than markers at the corners.
Specification
These are the values the editor enforces while you design, not figures collected from elsewhere — the same numbers its quiet-zone and resolution checks run on.
| Property | Value | In context |
|---|---|---|
| Minimum X-dimension | 0.25 mm | 0.0098 in · 10 thou |
| Quiet zone | Not required | No clear margin is required by the specification |
| Dimensionality | Matrix (2D) | Requires an imager or camera |
Aztec at 203, 300 and 600 dpi
A printer can only place whole dots, and 0.25 mm is not a whole number of them at any of these resolutions. What changes is how much a single dot of rounding costs you as a share of the narrow bar.
| Resolution | Narrow bar in dots | Printed as | Rounding error |
|---|---|---|---|
| 203 dpi | 2.00 | 2 dots | 0% |
| 300 dpi | 2.95 | 3 dots | 2% |
| 600 dpi | 5.91 | 6 dots | 2% |
What Aztec encodes
Text and binary data with built-in error correction, in a symbol that grows outward from a central bullseye. Because no surrounding clear space is required, the printed footprint is the symbol itself.
Where it is used
- Rail and airline tickets, including tickets displayed on a phone screen
- Transport and transit passes where print area is tightly constrained
- Any application where the quiet zone, not the symbol, is what does not fit
Check digit
None. Aztec uses Reed-Solomon error correction, with the proportion of the symbol given over to it configurable at encode time.
How Aztec fails in practice
- Treating no required quiet zone as no required contrast. The bullseye finder still has to be distinguishable from whatever surrounds it.
- Choosing it for consumer scanning without checking reader support, which is narrower than for QR Code.
- Printing it on a busy background, which the central finder pattern tolerates less well than corner-based finders do.
When to use something else
- QR Code — choose it instead when consumers will scan it and broad reader support matters more than the last millimetre.
- Data Matrix — choose it instead when you are marking a small industrial item and one module of quiet zone is affordable.
Questions about Aztec
- Does Aztec really need no quiet zone?
- Correct — the specification requires none, because the central bullseye finder pattern lets a reader locate the symbol without clear margins. That is its main advantage over QR Code, which needs four modules on every side.