QR code
Encyclopedia
A QR code is a type of matrix barcode (or two-dimensional code) first designed for the automotive industry. More recently, the system has become popular outside of the industry due to its fast readability and comparatively large storage capacity. The code consists of black modules arranged in a square pattern on a white background. The information encoded can be made up of any kind of data (e.g., binary, alphanumeric, or Kanji
symbols).
Created by Toyota subsidiary Denso
Wave in 1994 to track vehicles during the manufacturing process, the QR code is one of the most popular types of two-dimensional barcodes. It was designed to allow its contents to be decoded at high speed.
The technology has seen frequent use in Japan
; the United Kingdom
is the seventh-largest consumer of QR codes in the world.
At the application layer, there is some variation between implementations. NTT DoCoMo
has established de facto
standards for the encoding of URLs, contact information, and several other data types. The open-source "ZXing" project maintains a list of QR code data types.
(56 bits). Japanese immigration use encrypted QR codes when placing visas in passports.
long and use the Reed–Solomon error correction
algorithm with four error correction levels. The higher the error correction level, the less storage capacity. The following table lists the approximate error correction capability at each of the four levels:
Due to the design of Reed–Solomon codes and the use of 8-bit codewords, an individual code block cannot be more than 255 codewords in length. Since the larger QR symbols contain much more data than that, it is necessary to break the message up into multiple blocks. The largest possible block size is never used, though. The QR specification defines the block sizes so that no more than 15 errors can be corrected within each block. This limits the complexity of certain steps in the decoding algorithm. The code blocks are then interleaved together, making it less likely that localized damage to a QR symbol will overwhelm the capacity of any single block.
Thanks to error correction, it is possible to create artistic QR codes that still scan correctly, but contain intentional errors to make them more readable or attractive to the human eye, as well as to incorporate colors, logos and other features into the QR code block.
, and two complete copies are included in each QR symbol.
The message data is placed from right to left in a zigzag pattern, as shown below. In larger symbols, this is complicated by the presence of the alignment patterns and the use of multiple interleaved error-correction blocks.
Four-bit indicators are used to select the encoding mode and convey other information. Encoding modes can be mixed as needed within a QR symbol.
After each indicator that selects an encoding mode is a length field that tells how many characters are encoded in that mode. The number of bits in the length field depends on the encoding and the symbol version, as shown below.
Alphanumeric encoding mode stores a message more compactly than the byte mode, but cannot store lower-case letters and has only a limited selection of punctuation marks. Two characters are coded in an 11-bit value by this formula:
Alphanumeric character codes are as follows.
rights on QR codes, but has chosen not to exercise them.
In the USA, the granted QR code patent is , and in Japan . The European Patent Office granted patent EP0672994B1 to Denso Wave, which was then validated into French, British and German patents, all of which are still in force as of November 2011.
The term QR code itself is a registered trademark of Denso Wave Incorporated.
Standard QR code is the QR code standard for applications that possess the ability to handle large scans. A standard QR code can contain up to 7089 characters, though not all QR readers can accept that much data.
users (via mobile tagging
). Users may receive text, add a vCard
contact to their device, open a Uniform Resource Identifier
(URI), or compose an e-mail or text message after scanning QR codes. They can generate and print their own QR codes for others to scan and use by visiting one of several pay or free QR code-generating sites or apps. Google
has a popular API to generate QR codes, and apps for scanning QR codes can be found on nearly all smartphone devices.
QR codes storing addresses and Uniform Resource Locator
s (URLs) may appear in magazines, on signs, on buses, on business cards, or on almost any object about which users might need information. Users with a camera phone
equipped with the correct reader application can scan the image of the QR code to display text, contact information, connect to a wireless network
, or open a web page in the telephone's browser. This act of linking from physical world objects is termed hardlinking
or object hyperlinking
. QR Codes may also be linked to a location to track where a code has been scanned. Either the application that scans the QR Code retrieves the geo information by using GPS and cell tower triangulation (aGPS) or the URL encoded in the QR Code itself is associated with a location.
QR codes can be used in Google's mobile Android operating system via both their own Google Goggles
application or 3rd party barcode scanners like ZXing or Kaywa. The browser supports URI redirection, which allows QR codes to send metadata
to existing applications on the device. Nokia's Symbian
operating system features a barcode scanner which can read QR codes, while mbarcode is a QR code reader for the Maemo
operating system. In the Apple iOS, a QR code reader is not natively included, but more than fifty paid and free apps are available with both scanning capabilities and hard-linking to URI. With BlackBerry
devices, the App World application can natively scan QR codes and load any recognized Web URLs on the device's Web browser. Windows Phone 7.5
is able to scan QR codes through the Bing
search app.
In the USA, QR code usage is expanding. During the month of June 2011, according to one study, 14 million mobile users scanned a QR code or a barcode. Some 58% of those users scanned a QR or bar code from their home, while 39% scanned from retail stores; 53% of the 14 million users were men between the ages of 18 and 34.
While the adoption of QR codes in some markets has been slow to begin (particularly in markets such as the United States, where competing standards such as Data Matrix
exist), the technology is gaining some traction in the smartphone market. Many Android, Nokia, Blackberry handsets, and the Nintendo 3DS
, come with QR code readers installed. QR reader software is available for most mobile platforms. Moreover, there are a number of online QR code generators which enable users to create QR codes for their own needs.
, the reader's many permissions may allow use of the camera, full internet access, read/write contact data, GPS, read browser
history, read/write local storage, and global system changes.
Risks include linking to dangerous websites with browser exploits, enabling the microphone/camera/GPS and then streaming those feeds to a remote server, analysis of sensitive data (passwords, files, contacts, transactions), and sending email/SMS/IM messages or DDOS packets as part of a botnet
, corrupting privacy settings, stealing identity, and even containing malicious logic themselves such as JavaScript
or a virus. These actions may occur in the background while the user only sees the reader opening a seemingly harmless webpage.
Kanji
Kanji are the adopted logographic Chinese characters hanzi that are used in the modern Japanese writing system along with hiragana , katakana , Indo Arabic numerals, and the occasional use of the Latin alphabet...
symbols).
Created by Toyota subsidiary Denso
DENSO
is a global automotive components manufacturer headquartered in the city of Kariya, Aichi Prefecture, Japan. Established December 16, 1949 as , in 1996 the company became DENSO Corporation worldwide...
Wave in 1994 to track vehicles during the manufacturing process, the QR code is one of the most popular types of two-dimensional barcodes. It was designed to allow its contents to be decoded at high speed.
The technology has seen frequent use in Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
; the United Kingdom
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...
is the seventh-largest consumer of QR codes in the world.
Standards
There are several standards in documents covering the physical encoding of QR codes:- October 1997 — AIM (Association for Automatic Identification and Mobility) International
- January 1999 — JISJapanese Industrial StandardsJapanese Industrial Standards specifies the standards used for industrial activities in Japan.The standardization process is coordinated by Japanese Industrial Standards Committee and published through Japanese Standards Association.-History:...
X 0510 - June 2000 — ISOInternational Organization for StandardizationThe International Organization for Standardization , widely known as ISO, is an international standard-setting body composed of representatives from various national standards organizations. Founded on February 23, 1947, the organization promulgates worldwide proprietary, industrial and commercial...
/IEC 18004:2000 Information technology — Automatic identification and data capture techniques — Bar code symbology — QR code (now withdrawn)
Defines QR code models 1 and 2 symbols. - September 1, 2006 — 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.
At the application layer, there is some variation between implementations. NTT DoCoMo
NTT DoCoMo
is the predominant mobile phone operator in Japan. The name is officially an abbreviation of the phrase, "do communications over the mobile network", and is also from a compound word dokomo, meaning "everywhere" in Japanese. Docomo provides phone, video phone , i-mode , and mail services...
has established de facto
De facto
De facto is a Latin expression that means "concerning fact." In law, it often means "in practice but not necessarily ordained by law" or "in practice or actuality, but not officially established." It is commonly used in contrast to de jure when referring to matters of law, governance, or...
standards for the encoding of URLs, contact information, and several other data types. The open-source "ZXing" project maintains a list of QR code data types.
Storage
The amount of data that can be stored in the QR code depends on the character set, version and error correction level. The maximum values for version 40 with error correction capacity level L are:| Numeric only | Max. 7,089 characters |
| Alphanumeric Alphanumeric Alphanumeric is a combination of alphabetic and numeric characters, and is used to describe the collection of Latin letters and Arabic digits or a text constructed from this collection. There are either 36 or 62 alphanumeric characters. The alphanumeric character set consists of the numbers 0 to... |
Max. 4,296 characters |
| Binary Binary numeral system The binary numeral system, or base-2 number system, represents numeric values using two symbols, 0 and 1. More specifically, the usual base-2 system is a positional notation with a radix of 2... (8 bits) |
Max. 2,953 bytes |
| Kanji Kanji Kanji are the adopted logographic Chinese characters hanzi that are used in the modern Japanese writing system along with hiragana , katakana , Indo Arabic numerals, and the occasional use of the Latin alphabet... /Kana Kana Kana are the syllabic Japanese scripts, as opposed to the logographic Chinese characters known in Japan as kanji and the Roman alphabet known as rōmaji... |
Max. 1,817 characters |
Encryption
Although encrypted QR codes are not very common, there are a few implementations. An Android app, for example, manages encryption and decryption of QR codes using DES algorithmData Encryption Standard
The Data Encryption Standard is a block cipher that uses shared secret encryption. It was selected by the National Bureau of Standards as an official Federal Information Processing Standard for the United States in 1976 and which has subsequently enjoyed widespread use internationally. It is...
(56 bits). Japanese immigration use encrypted QR codes when placing visas in passports.
Error correction
Codewords are 8 bitsOctet (computing)
An octet is a unit of digital information in computing and telecommunications that consists of eight bits. The term is often used when the term byte might be ambiguous, as there is no standard for the size of the byte.-Overview:...
long and use the Reed–Solomon error correction
Reed–Solomon error correction
In coding theory, Reed–Solomon codes are non-binary cyclic error-correcting codes invented by Irving S. Reed and Gustave Solomon. They described a systematic way of building codes that could detect and correct multiple random symbol errors...
algorithm with four error correction levels. The higher the error correction level, the less storage capacity. The following table lists the approximate error correction capability at each of the four levels:
| 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. |
Due to the design of Reed–Solomon codes and the use of 8-bit codewords, an individual code block cannot be more than 255 codewords in length. Since the larger QR symbols contain much more data than that, it is necessary to break the message up into multiple blocks. The largest possible block size is never used, though. The QR specification defines the block sizes so that no more than 15 errors can be corrected within each block. This limits the complexity of certain steps in the decoding algorithm. The code blocks are then interleaved together, making it less likely that localized damage to a QR symbol will overwhelm the capacity of any single block.
Thanks to error correction, it is possible to create artistic QR codes that still scan correctly, but contain intentional errors to make them more readable or attractive to the human eye, as well as to incorporate colors, logos and other features into the QR code block.
Encoding
The format information records two things: the error correction level and the mask pattern used for the symbol. Masking is used to break up patterns in the data area that might confuse a scanner, such as large blank areas or misleading features that look like the locator marks. The mask patterns are defined on a 6×6 grid that is repeated as necessary to cover the whole symbol. Modules corresponding to the dark areas of the mask are inverted. The format information is protected from errors with a BCH codeBCH code
In coding theory the BCH codes form a class of parameterised error-correcting codes which have been the subject of much academic attention in the last fifty years. BCH codes were invented in 1959 by Hocquenghem, and independently in 1960 by Bose and Ray-Chaudhuri...
, and two complete copies are included in each QR symbol.
The message data is placed from right to left in a zigzag pattern, as shown below. In larger symbols, this is complicated by the presence of the alignment patterns and the use of multiple interleaved error-correction blocks.
Four-bit indicators are used to select the encoding mode and convey other information. Encoding modes can be mixed as needed within a QR symbol.
| Indicator | Meaning |
|---|---|
| 0001 | Numeric encoding (10 bits per 3 digits) |
| 0010 | Alphanumeric encoding (11 bits per 2 characters) |
| 0100 | Byte encoding (8 bits per character) |
| 1000 | Kanji encoding (13 bits per character) |
| 0011 | Structured append (used to split a message across multiple QR symbols) |
| 0111 | Extended Channel Interpretation (select alternate character set or encoding) |
| 0101 | FNC1 in first position (see Code 128 Code 128 Code 128 is a very high-density barcode symbology. It is used for alphanumeric or numeric-only barcodes. It can encode all 128 characters of ASCII and, by use of an extension character , the Latin-1 characters defined in ISO/IEC 8859-1... for more information) |
| 1001 | FNC1 in second position |
| 0000 | End of message |
After each indicator that selects an encoding mode is a length field that tells how many characters are encoded in that mode. The number of bits in the length field depends on the encoding and the symbol version, as shown below.
| Encoding | Ver 1–9 | 10–26 | 27–40 |
|---|---|---|---|
| Numeric | 10 | 12 | 14 |
| Alphanumeric | 9 | 11 | 13 |
| Byte | 8 | 16 | 16 |
| Kanji | 8 | 10 | 12 |
Alphanumeric encoding mode stores a message more compactly than the byte mode, but cannot store lower-case letters and has only a limited selection of punctuation marks. Two characters are coded in an 11-bit value by this formula:
- V = 45 × C1 + C2
Alphanumeric character codes are as follows.
| Code | Character | Code | Character | Code | Character | Code | Character | Code | Character |
|---|---|---|---|---|---|---|---|---|---|
| 0 | 0 | 9 | 9 | 18 | I | 27 | R | 36 | space |
| 1 | 1 | 10 | A | 19 | J | 28 | S | 37 | $ |
| 2 | 2 | 11 | B | 20 | K | 29 | T | 38 | |
| 3 | 3 | 12 | C | 21 | L | 30 | U | 39 | * |
| 4 | 4 | 13 | D | 22 | M | 31 | V | 40 | + |
| 5 | 5 | 14 | E | 23 | N | 32 | W | 41 | - |
| 6 | 6 | 15 | F | 24 | O | 33 | X | 42 | . |
| 7 | 7 | 16 | G | 25 | P | 34 | Y | 43 | / |
| 8 | 8 | 17 | H | 26 | Q | 35 | Z | 44 | |
License
The use of QR codes is free of any license. The QR code is clearly defined and published as an ISO standard. Denso Wave owns the patentPatent
A patent is a form of intellectual property. It consists of a set of exclusive rights granted by a sovereign state to an inventor or their assignee for a limited period of time in exchange for the public disclosure of an invention....
rights on QR codes, but has chosen not to exercise them.
In the USA, the granted QR code patent is , and in Japan . The European Patent Office granted patent EP0672994B1 to Denso Wave, which was then validated into French, British and German patents, all of which are still in force as of November 2011.
The term QR code itself is a registered trademark of Denso Wave Incorporated.
Variants
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 codes as well. The highest of these can hold 35 numeric characters.Standard QR code is the QR code standard for applications that possess the ability to handle large scans. A standard QR code can contain up to 7089 characters, though not all QR readers can accept that much data.
Uses
Although initially used to track parts in vehicle manufacturing, QR codes are now used over a much wider range of applications, including commercial tracking, entertainment and transport ticketing, product marketing and in-store product labeling. Many of these applications target mobile-phoneMobile phone
A mobile phone is a device which can make and receive telephone calls over a radio link whilst moving around a wide geographic area. It does so by connecting to a cellular network provided by a mobile network operator...
users (via mobile tagging
Mobile tagging
Mobile tagging is the process of providing data read from tags for display on mobile devices, commonly encoded in a two-dimensional barcode, using the camera of a camera phone as the reader device. The contents of the tag code is usually a URL for information addressed and accessible through...
). Users may receive text, add a vCard
VCard
vCard is a file format standard for electronic business cards. vCards are often attached to e-mail messages, but can be exchanged in other ways, such as on the World Wide Web or Instant Messaging...
contact to their device, open a Uniform Resource Identifier
Uniform Resource Identifier
In computing, a uniform resource identifier is a string of characters used to identify a name or a resource on the Internet. Such identification enables interaction with representations of the resource over a network using specific protocols...
(URI), or compose an e-mail or text message after scanning QR codes. They can generate and print their own QR codes for others to scan and use by visiting one of several pay or free QR code-generating sites or apps. Google
Google
Google Inc. is an American multinational public corporation invested in Internet search, cloud computing, and advertising technologies. Google hosts and develops a number of Internet-based services and products, and generates profit primarily from advertising through its AdWords program...
has a popular API to generate QR codes, and apps for scanning QR codes can be found on nearly all smartphone devices.
QR codes storing addresses and Uniform Resource Locator
Uniform Resource Locator
In computing, a uniform resource locator or universal resource locator is a specific character string that constitutes a reference to an Internet resource....
s (URLs) may appear in magazines, on signs, on buses, on business cards, or on almost any object about which users might need information. Users with a camera phone
Camera phone
A camera phone is a mobile phone which is able to capture still photographs . Since early in the 21st century the majority of mobile phones in use are camera phones....
equipped with the correct reader application can scan the image of the QR code to display text, contact information, connect to a wireless network
Wireless LAN
A wireless local area network links two or more devices using some wireless distribution method , and usually providing a connection through an access point to the wider internet. This gives users the mobility to move around within a local coverage area and still be connected to the network...
, or open a web page in the telephone's browser. This act of linking from physical world objects is termed hardlinking
Hardlink (homonymy)
A hardlink is one of several methods of object hyperlinking including graphical tags , SMS tags and RFID tags. The hardlink method establishes a reference link between a physical world object and a .mobi web page just as a traditional hyperlink establishes an electronic reference to information on...
or object hyperlinking
Object hyperlinking
Object hyperlinking is a neologism that usually refers to extending the Internet to objects and locations in the real world. The current Internet does not extend beyond the electronic world. Object hyperlinking aims to extend the Internet to the real world by attaching object tags with URLs as...
. QR Codes may also be linked to a location to track where a code has been scanned. Either the application that scans the QR Code retrieves the geo information by using GPS and cell tower triangulation (aGPS) or the URL encoded in the QR Code itself is associated with a location.
QR codes can be used in Google's mobile Android operating system via both their own Google Goggles
Google Goggles
Google Goggles is a downloadable image recognition application created by Google Inc. which can be currently found on the Mobile Apps page of Google Mobile. It is used for searches based on pictures taken by handheld devices...
application or 3rd party barcode scanners like ZXing or Kaywa. The browser supports URI redirection, which allows QR codes to send metadata
Metadata
The term metadata is an ambiguous term which is used for two fundamentally different concepts . Although the expression "data about data" is often used, it does not apply to both in the same way. Structural metadata, the design and specification of data structures, cannot be about data, because at...
to existing applications on the device. Nokia's Symbian
Symbian
Symbian is a mobile operating system and computing platform designed for smartphones and currently maintained by Accenture. The Symbian platform is the successor to Symbian OS and Nokia Series 60; unlike Symbian OS, which needed an additional user interface system, Symbian includes a user...
operating system features a barcode scanner which can read QR codes, while mbarcode is a QR code reader for the Maemo
Maemo
Maemo is a software platform developed by the Maemo community for smartphones and Internet tablets. It is based on the Debian Linux distribution, but has no relation to it...
operating system. In the Apple iOS, a QR code reader is not natively included, but more than fifty paid and free apps are available with both scanning capabilities and hard-linking to URI. With BlackBerry
BlackBerry
BlackBerry is a line of mobile email and smartphone devices developed and designed by Canadian company Research In Motion since 1999.BlackBerry devices are smartphones, designed to function as personal digital assistants, portable media players, internet browsers, gaming devices, and much more...
devices, the App World application can natively scan QR codes and load any recognized Web URLs on the device's Web browser. Windows Phone 7.5
Windows Phone 7.5
Windows Phone 7.5 is a major software update for Windows Phone, the mobile operating system by Microsoft. Although the OS internally identifies itself as version 7.1, it is marketed as version 7.5 in all published materials intended for end-users...
is able to scan QR codes through the Bing
Bing
Bing is a web search engine from Microsoft.Bing may also refer to:* An onomatopœia of a bell sound* Bing cherry, a variety of cherry* Bing , Chinese flatbread* Bing , a German company that manufactured toys and kitchen utensils...
search app.
In the USA, QR code usage is expanding. During the month of June 2011, according to one study, 14 million mobile users scanned a QR code or a barcode. Some 58% of those users scanned a QR or bar code from their home, while 39% scanned from retail stores; 53% of the 14 million users were men between the ages of 18 and 34.
While the adoption of QR codes in some markets has been slow to begin (particularly in markets such as the United States, where competing standards such as Data Matrix
Data Matrix
A Data Matrix code is a two-dimensional matrix barcode consisting of black and white "cells" or modules arranged in either a square or rectangular pattern. The information to be encoded can be text or raw data. Usual data size is from a few bytes up to 1556 bytes. The length of the encoded data...
exist), the technology is gaining some traction in the smartphone market. Many Android, Nokia, Blackberry handsets, and the Nintendo 3DS
Nintendo 3DS
The is a portable game console produced by Nintendo. The autostereoscopic device is able to project stereoscopic 3D effects without the use of 3D glasses or any additional accessories. The Nintendo 3DS features backward compatibility with Nintendo DS series software, including Nintendo DSi software...
, come with QR code readers installed. QR reader software is available for most mobile platforms. Moreover, there are a number of online QR code generators which enable users to create QR codes for their own needs.
Risks
Malicious QR codes combined with a permissive reader can put a computer's contents and user's privacy at risk. They are easily created and may be affixed over legitimate QR codes. On a smartphoneSmartphone
A smartphone is a high-end mobile phone built on a mobile computing platform, with more advanced computing ability and connectivity than a contemporary feature phone. The first smartphones were devices that mainly combined the functions of a personal digital assistant and a mobile phone or camera...
, the reader's many permissions may allow use of the camera, full internet access, read/write contact data, GPS, read browser
Browser
To browse or a browser may, among other concepts, refer to:*Browse, , a kind of orienting strategy in animals and human beings*Browsing , a type of herbivory*A user interface on a computer that allows navigation of objects...
history, read/write local storage, and global system changes.
Risks include linking to dangerous websites with browser exploits, enabling the microphone/camera/GPS and then streaming those feeds to a remote server, analysis of sensitive data (passwords, files, contacts, transactions), and sending email/SMS/IM messages or DDOS packets as part of a botnet
Botnet
A botnet is a collection of compromised computers connected to the Internet. Termed "bots," they are generally used for malicious purposes. When a computer becomes compromised, it becomes a part of a botnet...
, corrupting privacy settings, stealing identity, and even containing malicious logic themselves such as JavaScript
JavaScript
JavaScript is a prototype-based scripting language that is dynamic, weakly typed and has first-class functions. It is a multi-paradigm language, supporting object-oriented, imperative, and functional programming styles....
or a virus. These actions may occur in the background while the user only sees the reader opening a seemingly harmless webpage.