Aztec Code is a type of 2D barcode invented by Andrew Longacre, Jr. and Robert Hussey in 1995.[1] The code was published by AIM, Inc. in 1997. Although the Aztec code is patented,[1] it has been released to the public domain.
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The symbol is built on a square grid with a bulls-eye pattern at its centre for locating the code. Data is encoded in concentric square rings around the bulls-eye pattern. The central bulls-eye is 9×9 or 13×13 pixels, and one row of pixels around that encodes basic coding parameters, producing a "core" of 11×11 or 15×15 squares. Data is added in "layers", each one containing 2 rings of pixels, giving total sizes of 15×15, 19×19, 23×23, etc.
The corners of the core include orientation marks, allowing the code to be read if rotated or reflected. Decoding begins at the corner with three black pixels, and proceeds clockwise to the corners with two, one and zero black pixels. The variable pixels in the central core encode the size, so it is not necessary to mark the boundary of the code with a blank "quiet zone", although some bar code readers require one.
The compact Aztec code core supports symbols from 15×15 (room for 13 digits or 12 letters) through 27×27. There is additionally a special 11×11 "rune" that encodes one byte of information. The full core supports sizes up to 151x151, which can encode 3832 digits, 3067 letters, or 1914 bytes of data.
The level of Reed–Solomon error correction[2] 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.
Standard: ISO/IEC 24778 (published February 2008)
All 8-bit values can be encoded. The default interpretation shall be:
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.
Compact encoding modes are defined for storing text with five bits per character, and numeric data with four bits per character.
An Aztec code barcode is used by Eurostar, Deutsche Bahn, Trenitalia, Nederlandse Spoorwegen, PKP Intercity, Virgin Trains, Swiss Federal Railways, SNCF and its subsidiary iDTGV for tickets sold online and printed out by customers. An Aztec code barcode is used by Heathrow Express, East Coast, and VR Group in tickets delivered to mobile phones and displayed on their screens, and on self print tickets. The barcode is scanned by a handheld scanner by on-train staff to validate the ticket.
The Aztec Code has been selected by the airline industry (IATA's BCBP standard) for the electronic boarding passes. Several airlines send Aztec Codes to passengers' mobile phones for ticketing purposes, relating to online (or paperless) ticketing. Air New Zealand will be using the code domestically for ticketing, but this deployment is still in progress.[3]
Car registration documents in Poland bear an encrypted summary encoded as Aztec Code. Works are underway to enable car insurance companies to automatically fill in the relevant information based on digital photographs of the document as the first step of closing a new insurance contract.
Many bills in Canada are now using this technology as well, including EastLink (company), Shaw Cable, Bell Aliant and many more.
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