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[[File:QR code for mobile English Wikipedia.svg|thumb|A QR code for the [[URL]] of the [[English Wikipedia]] Mobile main page|alt=A QR code for the URL of the English Wikipedia Mobile main page]]
A '''QR code,''' (short for '''quick-response code''',<ref>{{cite interview |last=Hara |first=Masahiro |subject-link=Masahiro Hara |interviewer-last=Muller |interviewer-first=Derek |interviewer-link=Derek Muller |title=I used to hate QR codes. But they're actually genius |date=1 October 2024 |at=34:09 |url=https://www.youtube.com/watch?v=w5ebcowAJD8&t=2049 |access-date=1 October 2024 |quote=The biggest feature of QR codes is that they can be read quickly. It's called Quick Response because it reacts quickly.}}</ref>code) is a type of two-dimensional [[Barcode#Matrix (2D) codes|matrix barcode]] invented in 1994 by [[Masahiro Hara]] of the [[Japan]]eseJapanese company [[Denso#DENSO Wave|Denso Wave]] for labelling automobile parts.<ref>{{Cite journal|last1=Hung|first1=Shih-Hsuan|last2=Yao|first2=Chih-Yuan|last3=Fang|first3=Yu-Jen|last4=Tan|first4=Ping|last5=Lee|first5=RuenRone|last6=Sheffer|first6=Alla|last7=Chu|first7=Hung-Kuo|date=2020-09-01|title=Micrography QR Codes|url=https://ieeexplore.ieee.org/document/8632711|journal=IEEE Transactions on Visualization and Computer Graphics|volume=26|issue=9|pages=2834–2847|doi=10.1109/TVCG.2019.2896895|issn=1077-2626|pmid=30716038|s2cid=73433883|access-date=21 April 2021|archive-date=21 April 2021|archive-url=https://web.archive.org/web/20210421010504/https://ieeexplore.ieee.org/document/8632711/|url-status=live}}</ref><ref>{{Cite journal|last1=Chen|first1=Rongjun|last2=Yu|first2=Yongxing|last3=Xu|first3=Xiansheng|last4=Wang|first4=Leijun|last5=Zhao|first5=Huimin|last6=Tan|first6=Hong-Zhou|date=2019-12-11|title=AdaptiveIt Binarizationconsists of QR Code Images for Fast Automatic Sorting in Warehouse Systems|journal=Sensors|volume=19|issue=24|pages=5466|doi=10.3390/s19245466|pmc=6960674|pmid=31835866|bibcode=2019Senso..19.5466C |doi-access=free}}</ref> It features black squares arranged on a white background with [[fiducial markers]], making it readable by imaging devices likesuch as cameras,. andData from the code is processed using [[Reed–Solomon error correction]] until the image can be appropriatelyaccurately interpreted. The required datainformation is then extracted from patterns that are present in both the horizontal and the vertical components of the QR image.<ref name=autogenerated1/>
WhereasUnlike a traditional barcode, is a machine-readable optical image thatwhich contains information specific to the labeledlabelled item, thea QR code containscan thestore data for a locator, an identifier, andor web-tracking purposes. To store data efficiently, QR codes usesupport four standardized modes of encoding: [[Number|numeric]], [[Alphanumericals|alphanumeric]], [[Byte pair encoding|byte]] or [[Binary number|/binary]], and [[kanji]].<ref name="QRCodefeatures">{{cite web |url=http://www.qrcode.com/en/qrfeature.html |title=QR Code features |publisher=Denso-Wave |access-date=3 October 2011 |archive-url=https://web.archive.org/web/20130129064920/http://www.qrcode.com/en/qrfeature.html |archive-date=2013-01-29}}</ref>
Compared to standard [[Universal Product Code|UPC barcodes]], the QR labeling system was applied beyond the automobile industry because of faster reading of the optical image and greater data-storage capacity in applications such as product tracking, item identification, time tracking, document management, and general marketing.<ref name=autogenerated1>{{cite web |url=http://www.nacs.org/LinkClick.aspx?fileticket=D1FpVAvvJuo%3D&tabid=1426&mid=4802 |title=QR Code Essentials |publisher=Denso ADC |year=2011 |access-date=12 March 2013 |url-status=live |archive-url=https://web.archive.org/web/20130512180619/http://www.nacs.org/LinkClick.aspx?fileticket=D1FpVAvvJuo%3d&tabid=1426&mid=4802 |archive-date=12 May 2013}}</ref>
Compared to standard UPC barcodes, QR codes offer faster reading speed and greater data-storage capacity. This has led to their use beyond the automobile industry in applications such as product tracking, item identification, time tracking, document management, and general marketing.
== History ==
=== Encoding ===
====Format information and masking====
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 grid that is repeated as necessary to cover the whole symbol. Modules corresponding to the dark areas of the mask are inverted. The 5-bit format information is protected from errors with a [[BCH code]], and two complete copies are included in each QR symbol.<ref name="autogenerated1">{{cite web |year=2011 |title=QR Code Essentials |url=http://www.nacs.org/LinkClick.aspx?fileticket=D1FpVAvvJuo%3D&tabid=1426&mid=4802 |url-status=live |archive-url=https://web.archive.org/web/20130512180619/http://www.nacs.org/LinkClick.aspx?fileticket=D1FpVAvvJuo%3d&tabid=1426&mid=4802 |archive-date=12 May 2013 |access-date=12 March 2013 |publisher=Denso ADC}}</ref> A (15,5) triple error-correcting BCH code over {{math|GF(2<sup>4</sup>)}} is used, having the generator polynomial <math>g(x)=x^{10}+x^8+x^5+x^4+x^2+x+1</math>. It can correct at most 3 bit-errors out of the 5 data bits. There are a total of 15 bits in this BCH code (10 bits are added for error correction). This 15-bit code is itself X-ORed with a fixed 15-bit mask pattern ('''101010000010010''') to prevent an all-zero string.
====Error correction bytes====
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