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QR Code

The QR Code for Wikipedia (EN) Main Page

A QR Code is a matrix code (or two-dimensional bar code) created by Japanese corporation Denso-Wave in 1994. The "QR" is derived from "Quick Response", as the creator intended the code to allow its contents to be decoded at high speed. QR Codes are common in Japan, where they are currently the most popular type of two dimensional codes.

Overview
Standards
License
Storage
Micro QR Code
Design QR
Making QR Codes (Encoding)
See also
References
External links

Overview

Structure of a QR code, highlighting functional elements.

Although initially used for tracking parts in vehicle manufacturing, QR Codes are now used in a much broader context, including both commercial tracking applications and convenience-oriented applications aimed at mobile phone users (known as mobile tagging). QR Codes storing addresses and URLs may appear in magazines, on signs, buses, business cards or just about any object that users might need information about. Users with a camera phone equipped with the correct reader software can scan the image of the QR Code causing the phone's browser to launch and redirect to the programmed URL. This act of linking from physical world objects is known as a hardlink or physical world hyperlinks. Users can also generate and print their own QR Code for others to scan and use by visiting one of several free QR Code generating sites.

Standards

QR Code standards has been standardised several times.^[1]

October 1997 - AIM International ISS QR Code
January 1999 - JIS X 0510
June 2000 - ISO/IEC 18004:2000 Information technology — Automatic identification and data capture techniques — Bar code symbology — QR Code (now withdrawn)
Defines QR Code Model 1 and QR Code Model 2 symbols.
2006-09-01 - ISO/IEC 18004:2006 Information technology — Automatic identification and data capture techniques — QR Code 2005 bar code symbology specification
Defines QR Code 2005 symbols, an extension of QR Code Model 2. Does not specify how to read QR Code Model 1 symbols, or require this for compliance.

License

"QR Code is open in the sense that the specification of QR Code is disclosed and that the patent right owned by Denso Wave is not exercised." ^[1] The Japanese website goes on to state that the term QR Code itself is a "registered trademark of Denso Wave Incorporated in Japan and other countries". ^[2]

Storage

QR Code data capacity^[3]
Numeric only	Max. 7,089 characters
Alphanumeric	Max. 4,296 characters
Binary (8 bits)	Max. 2,953 bytes
Kanji/Kana	Max. 1,817 characters

Error correction capacity
Level L	7% of codewords can be restored.
Level M	15% of codewords can be restored.
Level Q	25% of codewords can be restored.
Level H	30% of codewords can be restored.

QR codes use the Reed?Solomon error correction. The example below illustrates how the QR code handles distortion. Pixels were either added or removed from the original code to examine the borderline distortion level. Both of the altered images remain recognisable using "Level L" error correction.

<gallery> Image:QRorg.png|Source code. Image:QRmin.png|Data removed. Image:QRmax.png|Data added. </gallery>

Micro QR Code

Micro QR Code is a smaller version of the QR Code standard for applications with less ability to handle large scans.

There are different forms of Micro QR Code as well. The highest of these can hold 35 characters.

Design QR

QR Code with a face design.

The design of QR makes it possible to incorporate eye-catching images of logos, characters, or photos into QR code, without losing any information of the code.

Colorized QR-code version of a Lewis Carroll poem.

The colorized image represents the first 12 stanzas of Lewis Carroll's, "The Walrus and the Carpenter". Encoded in binary mode with "Level M" error correction it contains approximately 2300 characters but, due to the density of the information, decoding it would require a high resolution image that is unavailable to many QR Code readers (particularly mobile phones).

British popgroup Pet Shop Boys used QR-code for the artwork of their download-only single Integral in 2007. The videoclip for the song also features QR-code. When the codes are scanned correctly, users are being redirected to Web pages about the British national identity card plans.

Making QR Codes (Encoding)

There are many tools that are available for encoding custom QR Codes. Using these tools it is possible to create QR Codes that represent a phone number, sms text message, phone number, and many other functions.