QR Code
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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 code.
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[edit] Overview
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Although initially used for tracking parts in vehicle manufacturing, QR Codes are now used in a much broader context spanning both commercial tracking applications as well as convenience-oriented applications aimed at mobile phone users. QR Codes storing addresses and URLs may appear in magazines, on signs, buses, business cards or just about any object that a user might need information about. A user having 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. A user can also generate and print one's own QR Code for others to scan and use by visiting one of several free QR Code generating sites.
The Japanese standard for QR Codes, JIS X 0510, was released in January of 1999, and a corresponding ISO International Standard, ISO/IEC 18004, was approved in June of 2000. The standard was updated in 2006 (ISO/IEC 18004:2006).
[edit] 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]
[edit] 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 images where data were altered are still recognisable and use the "L" level of error correction.
 Source code. |
 Data removed. |
 Data added. |
[edit] 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.
[edit] Design QR
Design QR makes it possible to incorporate eye-catching images of logos, characters, or photos into QR code, while calculating without losing any information of the code.
The colorized image represents the first 12 stanzas of the famous poem of Lewis Carroll "The Walrus and the Carpenter". This is about 2300 characters, encoded in binary mode, correction level M. Due to the information density of this code and the limited size and resolution the cameras on most QR code readers (particularly those on mobile phones), few QR Code readers would be able to successfully scan in a code containing this much information.
