Aztec Code

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Encoding: "This is an example Aztec symbol for Wikipedia."
Encoding: "This is an example Aztec symbol for Wikipedia."
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Aztec Code is a 2 dimensional matrix style bar code symbology. Aztec Code was invented by Andrew Longacre, Jr. of Welch Allyn Inc. in 1995 (later Hand Held Products Inc., now Honeywell Imaging and Mobility). The code was published by AIM International in 1997 and although the code is patented, it has been released to the public domain.

Contents

[edit] Encoding

The symbol is built on a square grid with a bulls-eye pattern at its centre for locating the code. Data is encoded in a series of circles around the bulls-eye pattern. Each additional circle completely surrounds the previous circle causing the symbol to grow in size as more data is encoded. A dark module is a binary 1 and a light module is a binary 0. The code is orientation independent.

The smallest Aztec Code symbol is 15x15 modules square, and the largest is 151x151. The smallest Aztec Code symbol encodes 13 numeric or 12 alphabetic characters. The largest Aztec Code symbol encodes 3832 numeric or 3067 alphabetic characters or 1914 bytes of data. No empty zone is required outside the bounds of the symbol.

The level of Reed–Solomon error correction[1] is configurable, from 5% to 95% of the data region. The recommended level is 23% of symbol capacity plus codewords.

Aztec Code is supposed to be robust according to various printer technologies. It is also well suited for displays of cell phones and other mobile devices.

[edit] Character set

  1. All 8-bit values can be encoded. The default interpretation shall be:
    1. for values 0 - 127, ANSI X3.4 (i.e., ASCII) and
    2. for values 128 - 255, ISO 8859-1: Latin Alphabet No. 1.
      This corresponds to ECI 000003.
  2. Two non-data characters can be encoded, FNC1 for compatibility with some existing applications and ECI, escape sequence for the standardized encoding of message interpretation information.

[edit] Usage

An Aztec code barcode is used by Deutsche Bahn and by Swiss Federal Railways for tickets sold online and printed out by customers. The barcode is scanned by a handheld scanner by on-train staff to validate the ticket.

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