QR code: Difference between revisions

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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

A QR code (short for Quick Response code) is a type of two-dimensional matrix barcode invented in 1994 by Masahiro Hara of the Japanese company Denso Wave for labelling automobile parts. It consists of black squares arranged on a white background with fiducial markers, making it readable by imaging devices such as cameras. Data from the code is processed using Reed–Solomon error correction until the image can be accurately interpreted. The required information is extracted from patterns present in both the horizontal and vertical components of the QR image.

|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> is a type of two-dimensional [[Barcode#Matrix (2D) codes|matrix barcode]] invented in 1994 by [[Masahiro Hara]] of the [[Japan]]ese 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|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|bibcode=2020ITVCG..26.2834H |s2cid=73433883}}</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=Adaptive Binarization 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 on a white background with [[fiducial markers]], readable by imaging devices like cameras, and processed using [[Reed–Solomon error correction]] until the image can be appropriately interpreted. The required data is then extracted from patterns that are present in both the horizontal and the vertical components of the QR image.<ref name=autogenerated1/>

UnlikeWhereas a traditional barcode, whichis a machine-readable optical image that contains information specific to the labelledlabeled item, athe QR code cancontains storethe data for a locator, an identifier, orand web-tracking purposes. To store data efficiently, QR codes supportuse 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 ==

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=== 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(2⁴)}} 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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=== Secure QR code{{anchor|SQR}} ===

Secure Quick Response Code (SQRSQRC) code is a QR code that contains a "private data" segment after the terminator instead of the specified filler bytes "ec 11".<ref>{{cite web|url=https://fukuchi.org/works/qrhack/qrhack1.html|title=Embedding Secret Data in QR Code|access-date=29 October 2018|archive-date=30 October 2018|archive-url=https://web.archive.org/web/20181030090645/https://fukuchi.org/works/qrhack/qrhack1.html|url-status=live}}</ref> This private data segment must be deciphered with an encryption key. This can be used to store private information and to manage a company's internal information.<ref>{{cite web|title=SQRC|url=http://www.qrcode.com/en/codes/sqrc.html|website=qrcode.com|access-date=26 December 2017|archive-date=1 January 2018|archive-url=https://web.archive.org/web/20180101191507/http://www.qrcode.com/en/codes/sqrc.html|url-status=live}}</ref>

=== Frame QR ===