PDF417 مقابل Aztec Code
PDF417 stacks rows of linear codewords and holds 1,850 alphanumeric characters; Aztec Code builds outward from a central bull's-eye, holds 3,832, and requires no quiet zone at all. Aztec is the stronger choice for codes shown on a phone screen, PDF417 for printed identity documents whose format is already specified.
Specification comparison
| Specification | PDF417 | Aztec Code |
|---|---|---|
| Classification | Stacked | 2D Matrix |
| Symbology family | Stacked Family | 2D Matrix Family |
| Year introduced | 1991 | 1995 |
| Developer | Ynjiun Wang (Symbol Technologies) | Andrew Longacre (Welch Allyn) |
| Data length | variable | variable |
| Variable length | Yes | Yes |
| Character set | Full ASCII + binary data | Full ASCII + binary data |
| Maximum capacity | 1,850 alphanumeric or 2,710 numeric characters | 3,832 alphanumeric or 3,067 numeric characters |
| GS1 data carrier | No | No |
| Unicode encoding | No | No |
| Binary data | Yes | Yes |
| Minimum X-dimension | 0.254 mm | 0.254 mm |
| Quiet zone | Two modules | None required |
| Aspect ratio | variable (3:1 to 1:3) | 1:1 (square) |
| Example payload | PDF417-BarcodeFYI | AztecCode2026 |
| Structure | Stacked rows of linear codewords | Concentric square matrix |
| Finder pattern | Start and stop patterns on every row | Central bull's-eye |
| Error correction | Nine selectable levels | Selectable from 5 to 95 percent, 23 percent by convention |
| Typical specification | AAMVA driver's licences, printed IATA boarding passes | European rail ticketing, mobile boarding passes |
Highlighted rows mark specifications where the two symbologies differ.
Two answers to the same problem
PDF417 is a stacked linear symbology. Each row is a short one-dimensional barcode with its own start pattern, stop pattern, and row indicator, and the rows sit one above another. A reader that catches rows out of order, or misses part of a row, still reconstructs the payload from the row indicators and the Reed-Solomon correction spread across the symbol. Symbol Technologies published the design in 1991.
quiet zone needed." data-category="2D & Matrix Symbologies">Aztec Code, developed by Andrew Longacre at Welch Allyn in 1995, is a true matrix code. Its finder is a set of concentric squares at the centre of the symbol, and data layers accumulate around that core as the payload grows. Placing the finder in the middle removes the need for a surrounding quiet zone, which is the single most consequential difference between the two formats in practice.
Capacity and error correction
Aztec reaches 3,832 alphanumeric or 3,067 numeric characters against 1,850 alphanumeric or 2,710 numeric for PDF417. Both offer selectable error correction: PDF417 defines nine levels, while Aztec allows the correction proportion to be set anywhere between 5 and 95 percent of symbol capacity, with 23 percent as the conventional default. For the few hundred characters typical of a ticket or boarding pass both formats sit comfortably within range, so the decision turns on form factor rather than capacity.
Screen scanning and quiet zones
The absence of a quiet zone requirement is why Aztec dominates mobile ticketing. A code rendered inside a phone application sits against whatever interface surrounds it, and the blank margin PDF417 needs cannot be guaranteed there. Aztec's central finder is also easier to acquire under the reflections, backlight variation, and off-axis angles common when a passenger holds a screen against a gate reader.
PDF417 answers a different constraint. Its aspect ratio is adjustable from 3:1 to 1:3, letting the symbol be shaped to the space available on a document, and its rows degrade gracefully when a printed card is scratched or creased across a single row.
Where each is specified
PDF417 is written into the AAMVA standard for North American driver's licences, into the IATA bar-coded boarding pass specification for printed passes, and into a range of government identity and vehicle documents. Aztec is specified for rail ticketing across most European operators and for boarding passes delivered to a mobile device. Neither is a GS1 data carrier, both accept binary payloads, and both use 0.254 mm modules at nominal size.
Which to choose
Choose PDF417
- A published specification such as AAMVA or the printed IATA pass fixes the document format.
- The symbol must be shaped to a narrow or wide area, using the 3:1 to 1:3 aspect range.
- The medium is printed card or paper where a quiet zone can be guaranteed.
Choose Aztec Code
- The code will be displayed on a phone screen, where no quiet zone can be reserved.
- Payloads approach or exceed the 1,850-character ceiling of PDF417.
- Readers must acquire the symbol at varying angles and brightness at a gate or turnstile.
Recommendation
For codes delivered to a screen, Aztec is the better engineering choice, because its interior finder removes the quiet zone dependency behind most mobile scan failures. For printed identity documents the format is usually dictated by the governing specification, and that specification is generally PDF417.