QR code

from Wikipedia, the free encyclopedia
QR code with a link to Wikipedia
The string
"de.wikipedia.org"
as a QR code.

Error correction: M

The QR code ( English Q uick R esponse , "rapid response" as a trademark term "QR Code") is a two-dimensional code , which the Japanese company Denso Wave was developed in 1994th Due to an automatic error correction, this method is very robust and therefore widespread. Further developments are the micro QR code , the secure QR code (SQRC), the iQR code and the frame QR code .

history

"Wikipedia is a project to build an encyclopedia from free content in over 270 languages, to which you can contribute with your knowledge." As a QR code

The QR code was developed for marking assemblies and components for logistics in the automobile production of the Toyota group. Denso, the company developing the QR code, has been cooperating with Toyota as a supplier for all electrical and electronic assemblies, among other things, since it was spun off from the group in 1949. The development of the 2D code was carried out by the subsidiary Denso Wave , which also develops identification systems and devices for mobile data acquisition. The QR code was developed in 1994 by Masahiro Hara and his team members Takayuki Nagaya, Motoaki Watabe, Tadao Nojiri and Yuji Uchiyama.

Masahiro Hara and his team won the audience award of the European Inventor Award of the European Patent Office in 2014 in the category "Non-European countries".

Basics

The QR code consists of a square matrix of black and white squares that represent the encoded data in binary . A special marking in three of the four corners of the square indicates the orientation. The data in the QR code are enhanced by an error-correcting code. This tolerates the loss of up to 30% of the code, i.e. i.e. it can still be decoded then.

Standards

There are several standards that describe the coding of QR codes.

  • March 10, 1995 - European patent number EP0672994
  • October 1997 - AIM (Association for Automatic Identification and Mobility) International
  • January 1999 - JIS X 0510
  • June 2000 - ISO / IEC 18004: 2000 (withdrawn)
    Defines QR code model 1 and QR code model 2
  • November 2004 - Extension of JIS X 0510 by micro QR code
  • September 1, 2006 - ISO / IEC 18004: 2006
    Defines QR Code 2005, an extension of QR Code Model 2; does not specify how QR code model 1 can be read, but builds on QR code model 1 specifications

The QR code is registered as a national standard in the following countries:

country default
Japan Japanese Industrial Standard JIS X 0510
China Chinese National Standard GB / T 18284
South Korea Korean National Standard KSXISOIEC 18004
Vietnam Vietnamese National Standard TCVN 7322
Singapore Singapore National Standard SS 543 ('09)

Aside from the official standards, NTT DoCoMo has defined de facto standards for the coding of URLs, contact information and other data types. The open source project “ZXing” maintains a list of QR code data types.

construction

QR code structure example

The code contains the version information (1) and the data format used (2). The data part (3) contains the coded data in redundant form. To delimit the field, the QR code has a specific pattern in only three of its corners (4.1). The reader recognizes the orientation from the missing pattern in the fourth corner. As the size of the code increases, more patterns (4.2) are added to make the alignment of the code easier to see. Between the three main position markings there is a line (4.3) made up of a sequence of strictly alternating bits, which defines the matrix. The white border (quiet zone) is also important to separate the code from other information.

Capacity and fault tolerance

The symbol elements are squares, of which at least 21 × 21 and a maximum of 177 × 177 elements are in the symbol. The edge zone (quiet zone) should be at least four elements wide. Larger content can be divided into up to 16 individual codes.

There are four error correction levels that allow reconstruction of 7% (level L) to 30% (level H) of damaged data. The error correction of the Reed-Solomon coding is used here. This property is used when creating so-called "design codes" (see section: Design QR code ).

Capacity of the different error correction levels
Level L (Low) 7% of the code words / data can be recovered
Level M (medium) 15% of the code words / data can be recovered
Level Q (quartiles) 25% of the code words / data can be recovered
Level H (high) 30% of the code words / data can be recovered

The maximum information content of a QR code (177 × 177 elements, error correction level "L") is 23,648 bits (2,953 bytes). According to the manufacturer, this can be used to encode 7089 decimal digits , 4296 alphanumeric characters or 1817 Kanji / Kana characters .

There is a separate coding method for Kanji and Kana characters ( U + 4E00 to U + 9FFF , U + 3040 to U + 309F , U + 30A0 to U + 30FF ) .

The micro QR code with a size between 11 × 11 and 17 × 17 elements takes up to 35 digits with a border width of at least two elements.

License

Japanese residence permit (Landing Permission) with (for Wikipedia) anonymous QR code

The use of the QR code is license-free and free of charge. The specifications were published by Denso Wave and are available from the International Organization for Standardization in Switzerland. The name “QR Code” is specially protected in Japan, the United States of America, Australia and Europe as a registered trademark of Denso Wave Incorporated. A corresponding notice should be attached when using.

The QR code is established as a public standard. It is very widespread in Japan, and you can find it on almost every advertising poster there. The Japanese government also uses the QR code. For example, the Japanese immigration authorities use the QR code with encoded data for the visa, which is stuck into the passport upon entry.

presentation

The QR code can be printed with all common methods without any problems. As with the barcode , however , the highest possible contrast is important, ideally in black and white. An inverse display is also possible, depending on the capabilities of the reader used. It is also possible to print the code in color. However, it must be ensured that the code, viewed as a halftone image or as a line image , has a uniform contrast. The QR code is also increasingly being affixed to products using the so-called " direct marking " process. For example, they are burned directly onto the surface of the material to be marked with a laser . These QR codes can be very small and are very durable.

There is no limit to the size of the QR code as long as the reader can record the image in full format and differentiated. Billboards and entire house facades have already been provided with a single QR code.

Reading codes

Reading QR codes consists of two steps:

  1. Generating a digital image of the QR encoded data, e.g. B. with the help of a digital camera.
  2. Converting the coded data contained in the picture into text form (decoding).

Mobile phones

Many cell phones , PDAs, and similar devices have built-in cameras. With this and suitable software from an app store , QR codes can be decoded and interpreted if necessary, e.g. B. automatically jump to a website. The process known as mobile tagging is extremely popular in Japan. It has been spreading in Europe since 2007.

Tagging process.jpg
Decoding a URL with a smartphone

The coded image of a web address , used in magazines, information leaflets or in large format on advertising posters is widespread . The advantage of this method is that tedious typing is no longer necessary. In addition to URLs, QR codes in practice contain, for example, telephone numbers, addresses, informative texts, premium SMS, vCards , WLAN access data or geodata .

The first QR code in Germany was published on October 16, 2007 by Spex - Magazin für Popkultur on the front page. The heading “What does this code tell us?” Opens an article that deals with the trend of 2D codes and how they work. The author describes the code as a sign of our times, as the QR code is used by both the fashion industry and the music and video industries.

On November 9, 2007, Die Welt Kompakt was the first printed newspaper to introduce QR codes. You can now see the QR code in many other newspapers and magazines.

scanner

Like barcode scanners, “scanner” is the common term for reading devices. The term "imager" is also common in the industry when it comes to a 2D device. They have a camera and a decoder. In addition, many devices offer aiming aid, often in the form of a laser-generated pattern that shows the reading field.

Special reading devices are also able to read QR codes that have been burned directly onto the material with a laser using the direct marking process . They have a high-resolution camera and a macro lens as well as special algorithms for eliminating display errors typical of the process.

software

If a digital QR image is already available, then all you need is software that analyzes the image and converts (decodes) the image. There are z. B. Online QR code decoder.

Generating codes

To generate a QR code, you need:

  • the text to be encoded
  • the desired level of error correction

The rough sequence is then:

  1. Based on the length of the text and the degree of error correction, you can determine how big the QR code has to be.
  2. You start with a white area on which all the elements of the QR code are gradually displayed.
  3. The recognition patterns that do not depend on the text are first applied to the surface. These are the position patterns, the alignment patterns and the synchronization lines.
  4. A bit sequence is generated from the text.
  5. In addition to the text bit sequence, a further bit sequence is generated for error correction.
  6. The text bit sequence is drawn together with the error correction bit sequence in the symbol where there is still space. This happens from right to left in serpentine lines.
  7. In order to ensure that the symbol contains approximately the same number of black and white pixels and to avoid patterns that make reading difficult, eight different masks are placed one after the other over the symbol. The mask that gives the best result is retained.
  8. Finally, the identification number of the mask used is drawn in the symbol.

Online QR code generator

A quick and easy way to create a QR code is to use an online QR code generator. A script converts text into code and creates the graphic. This means that practically anyone can easily create code.

QR codes can not only be generated as pixel graphics, but can also be composed of matching Unicode sub-elements.

Converting the text into a bit string

Because of the versatile application possibilities and the small size of QR codes, it was important to ensure that the coded text only needs little space. Depending on which characters appear in the text, the text can be encoded with different character sets:

  • binary ( byte- wise)
  • If the text consists of only digits (0–9), it takes up the least space. In this case, three digits are combined and saved as a 10-bit unit.
  • If the text only consists of digits (0–9), capital letters (A – Z) and nine other special characters (space, $,%, *, +, -, /,., :), two characters are combined and used as a 11-bit unit stored.
  • If the text only consists of characters that appear in ISO-8859-1 (including upper and lower case letters, numbers, many punctuation marks and combined letters for the Western European language area), each character is stored as an 8-bit unit.
  • If the text is only Kanji , each character is stored as a 13-bit unit.
  • In the rest of the cases it gets more complicated; the ECI character encoding is then used.

After the appropriate character set has been determined, the following information is written into the bit sequence:

  1. the identification number of the character set
  2. the number of characters the text has
  3. the text itself
  4. the end identifier; it is always 0000
  5. decompose the resulting bit sequence into 8-bit units; Fill up with zero bits at the end if necessary
  6. Filling up to the data capacity of the QR code version with the code words 11101100 and 00010001 alternately

example

In order to encode the text “Book of Fairy Tales”, the appropriate character set is first selected. In this case it is ISO-8859-1. This character set has the identification number 0100 .

The second step is to count how many characters the text contains. In this case there are 11 characters. For small QR codes, this number is encoded with 8 bits, i.e. 0000 1011 . With larger QR codes, the number would be encoded with 16 bits.

Then the individual characters are encoded. In the case of the ISO-8859-1 coding, look in the table for the character set to see which number this character has and write the number down. For the "M" this is 0100 1101 . The "ä" gets the number 1110 0100 , and so on.

The end is the end identifier. It is always 0000 , unless there is not enough space left. Then it is abbreviated.

Overall, the text “fairy tale book” becomes this bit sequence:

  • 0100
  • 0000 1011
  • 0100 1101 1110 0100 0111 0010 0110 0011 0110 1000 0110 0101 0110 1110 0110 0010 0111 0101 0110 0011 0110 1000
  • 0000

Split into 8-bit units and, if necessary, filler codes: 01000000 10110100 11011110 01000111 00100110 00110110 10000110 01010110 11100110 00100111 01010110 00110110 10000000 11101100 00010001 11101100 00010001 ...

Areas of application

QR code of the game "Munzee"

In addition to its original purpose, the use in production logistics, to QR codes are now finding in many other applications again: for example, as timetable information and navigation assistance to stops of public transport as an aid to the shopping list , the mark of pets or as mobile business card. QR codes are also becoming more and more popular in advertising, as additional information, for example product videos or websites with or without competitions, can be called up quickly or linked directly to the App Store with the option of downloading programs. In the museums of Canada , the codes are used to give visitors the opportunity to access information about individual exhibits or thematic complexes via the Internet. In 2012, an interactive first day cover with a series of stamps “Brand Individual” from a Leipzig mail order company was published for the first time . The QR code printed on the letter is used here as shop access. QR codes also help with so-called screen transfers , which describe the transfer of a website in the web browser of one device to another.

Initial approaches to the use of QR codes can also be seen in the area of ​​saving lives. For example, the QR code is now used to access the rescue card for cars.

In the Munzee scavenger hunt game , the QR codes and the GPS coordinates (GPS-enabled smartphone required) serve as a "location-based game" to earn points on the player's account when the QR codes are scanned . The QR codes are generated on the gaming platform and distributed in the real world.

In Berlin, QR codes were engraved on cobblestones at the Memorial to the Murdered Jews of Europe , where you can listen to the virtual concert composed for the Holocaust Memorial via an app.

A team of researchers from the state of South Dakota has developed an invisible special ink, which consists of a mixture of blue and green fluorescent inks with nanoparticles and is visible under a NIR laser. QR codes that are printed on banknotes or other securities with this ink could increase their security against forgery.

  • Information about a monument

  • Billboard
    with QR code

  • Interactive stamp
    with QR code

  • Our Father ,
    prayer as a QR code

hazards

Because the content of a QR code cannot be seen at first glance, it is possible to hide a link in it that leads the viewer to a malicious page after scanning or even unintentionally executes functions on their smartphone . However, this affects all common 2D codes that are used to encode web addresses, and is not a special feature of the QR code.

An attack carried out using such codes (“tags”) is commonly referred to as “atagging” . At the beginning of September 2010, attacks on cell phones with Android operating systems became known, in which the ICQ client “Jimm” could be downloaded via a link encoded in a QR code on a website . The software was infected with the Trojan-SMS.AndroidOS.Jifake.f trojan and unsolicited several chargeable SMS messages to a Russian premium service. The Federal Office for Information Security warned in early January 2013. taped QR codes on billboards, which could lead the user to rogue websites.

To protect against attacks, many current scanners only display the decoded QR code content instead of executing it immediately, for example following a link to open a page. However, many QR code scanners load the page in advance when the link is displayed in the browser, in order to e.g. B. to display the page title a short time after scanning before the actual call or to accelerate the display, which is why there is a certain risk potential even without a direct page call if the scan software is vulnerable when generating the preview.

By manipulating the coding for the exact number of characters contained in the QR code, it is theoretically possible to cause a buffer underrun or a buffer overflow in poorly programmed decoder software. Attacks via SQL injection would also be conceivable if the processing software does not have appropriate protective mechanisms.

A potential risk arises from the application software used, which processes the read data, but not from the QR code itself. The user, especially of mobile phones, also bears a high degree of risk through inexperienced handling of URLs encoded in QR codes at. All of the dangers mentioned apply equally to all 2D code systems from other manufacturers. By using the Secure QR Code , most sources of danger in professional applications can be largely eliminated.

Further developments

Example of a design QR code (linked to the German-language Wikipedia mobile page)

Design QR code

QR codes can be customized with a lettering, logo or image and by changing the color, or they can be designed graphically with more effort. The function is retained through a clever approach and misappropriation of the error correction. Such QR codes are often referred to as design QR codes or, in the case of more complex design, as custom QR codes . Alienated QR codes are often also referred to as iQR codes , which is factually incorrect, as the iQR code is its own, further developed variant of the QR code.

Design QR codes are not an official development of Denso Wave.

In the beginning, the design was often limited to a simple exchange of colors. In addition, lettering or a logo can be placed as a small pixel graphic, usually in the center of the QR code, or worked directly into it.

QR code from Wikipedia

Part of the code's data is simply overlaid by the graphic. The redundancy of the error correction in level "H" enables this on an area of ​​up to 30% of the entire code. From a technical point of view, the data part of a design QR code is already so disturbed by the overlaid graphics that real reading errors can no longer be compensated for.

Another possibility is to use mathematical processes to include a graphic in a QR code so that the QR code is error-free. For this purpose, the hyperlink is supplemented by a seemingly pointless anchor that has no function of its own.

By linking these processes, complex custom QR codes can now be generated with the focus on the design. QR codes are specifically adapted to existing corporate designs or integrated into marketing campaigns. Examples are advertisements that are dominated by a single, elaborately designed custom QR code, or company logos that are designed directly as custom QR codes. In 2009 Takashi Murakami designed such a corporate QR code on behalf of Louis Vuitton .

Overlaying logos or illustrations as well as own designs and alienations are legally questionable, as Denso Wave also holds its own patents for this. Denso Wave does not apply patent law to standard QR codes, but not to changed QR codes.

Micro QR code

The string
"Wikipedia" as a micro QR code, version M3, ECC level "L"

The micro QR code is a variant of the QR code that has been optimized for the smallest dimensions. It was introduced by Denso Wave in 2000. Instead of the familiar three orientation markings of the QR code, the micro QR code only has one in the upper left corner. A maximum of 35 digits or 21 alphanumeric characters can be encoded, but less space is required for this.

The following table contains information about the maximum capacity for the respective version and the corresponding level of error correction:

version Number of modules Error correction level redundancy Numeric characters Alphanumeric characters Binary characters (bytes) Kanji characters
M1 11 × 11 - 0% 5 - - -
M2 13 × 13 L. 7% 10 6th - -
M. 15% 8th 5 - -
M3 15 × 15 L. 7% 23 14th 9 6th
M. 15% 18th 11 7th 4th
M4 17 × 17 L. 7% 35 21st 15th 9
M. 15% 30th 18th 13 8th
Q 25% 21st 13 9 5

The micro QR code is standardized as JIS X 0510 (November 2004).

Secure QR code

The Secure QR Code (SQRC) is a QR code with an extended function for encrypting data content. Denso Wave introduced it in 2005. The SQRC is used in applications in which data content or parts of it should not be viewed by third parties. For this, the SQRC offers the option of encrypting the entire content or, alternatively, only part of the data it contains. The public (unencrypted) data in a SQRC can then also be read with normal QR code readers and mobile phones , while the encrypted information remains hidden. In order to be able to read the encrypted data, a reader is required that can decode Secure QR codes. The appropriate key must be saved in the reader.

The data is already encrypted when the SQRC is generated. The decryption is part of the decoder in the reader. Additional encryption software at the application level is therefore not required. A symmetric key (password) with a length of 8 bytes is required for encryption and decryption.

iQR code

Rectangular iQR code with 40 characters of data and ECC level "M".

With the iQR code, Denso Wave 2012 took up some of the advantages of the micro QR code as a further development of the normal QR code and, as a result, transferred the properties of the normal QR code. What was new at the time was that it was not necessarily set to a square shape, but could also assume that of a rectangle . This makes it easier, for example, to read cylindrical objects and use them where a classic barcode needs to be replaced by a 2D code, but there is no space for a square. The iQR code also offers a solution for applications that require a lot of data in a small space.

The maximum amount of data has been increased by more than a factor of 4.6 from 177 × 177 elements to 422 × 422 elements. This means that in the largest format (version 61) more than 40,000 numeric characters can be accommodated in a single code.

15 formats from 5 × 19 elements to 43 × 131 elements are available as rectangles. The largest format (version R15) can accommodate up to 1,202 numeric characters.

In addition, the iQR code is up to 30% smaller than a standard QR code with the same amount of encoded data. It is also even more compact than the micro QR code. The smallest possible format (version 1) has 9 × 9 elements and offers space for 6 characters.

Due to the supported characters, the content can be encoded according to ISO / IEC 15434 (Transfer Syntax). This enables the use of many data structures common in industry and trade, for example UN / EDIFACT segments, GS1 application identifier or ANS MH10.8.2 data identifier in accordance with ISO / IEC 15418.

For increased fault tolerance, the "T" level was also created, which enables the recovery of up to 60% destroyed data.

Capacity of the different error correction levels
Level L 7% of the code words / data can be recovered
Level M 15% of the code words / data can be recovered
Level Q 25% of the code words / data can be recovered
Level H 30% of the code words / data can be recovered
Level S 50% of the code words / data can be recovered
Level T 60% of the code words / data can be recovered

As with the QR code, the manufacturer Denso Wave planned to disclose the specification and free use as a public domain while respecting the trademark. In addition, registration as an ISO standard was sought.

On the Internet, personalized QR codes (so-called " design QR codes ", also colored and with integrated logos) are often referred to as iQR codes, which is factually incorrect.

Frame QR

Frame QR code with blank canvas
Frame QR code with a circular drawing area and Wikipedia logo

Frame QR is a further development of the QR code, which allows you to add your own logos or designs while maintaining redundancy. The drawing area to be kept free is already taken into account when creating the code and can take various forms.

A number of basic shapes (including square, circle, triangle, cross, heart, star with 5 or 6 points) are available as drawing areas, which can be varied by influencing the width, height and angle of rotation. However, you can also define your own shape as a drawing area.

For the design, the drawing area, the drawing area frame, the light and dark data points and the orientation markers can each be assigned their own colors. The matrix points, which are usually square, can also take the form of small circles.

The data matrix itself is placed around the drawing area and dimensioned so that all data are encoded in the selected redundancy level. In contrast to the so-called design QR codes, which take advantage of this redundancy, no data is lost and the redundancy is fully retained. The levels L, M, Q and H already used in the original QR code are also available as redundancy levels.

Frame QR is not compatible with the conventional QR code and therefore cannot be read with the usual scanners or smartphone applications. However, Denso Wave provides its own app for iOS and Android free of charge.

The QR code in art

Acrylic painting by Michael Weisser; working QR code leads to the recitation of a poem.

From 2007 the QR code also became an issue in contemporary art. Because it conveys a strong visual effect as a digital sign and connects the user with the Internet, it inspires creative people to experiment.

The Bremen media artist Michael Weisser started his research on the aesthetics and function of the QR code in 2007. In 2013 he developed QRs that were designed in color and shape and were declared works of art and designed as 33-QR thinking benches on the campus of the University of Applied Sciences in Kiel .

From 2009 the designer Frank Haase in Hemer used the QR code in graphics, pictures and objects. Haase guides the viewer to their own animations on the Internet via the original colored QR code. In 2009 the Berlin street artist Sweza used the QR in sprays. He sprayed the patterns as a stencil on house walls. By scanning the QR, the user was able to access electronic songs by the artist.

See also

literature

  • Bernhard Lenk: "QR Code" , Monika Lenk specialist book publisher, Kirchheim 2012, ISBN 978-3-935551-10-6 .
  • Michael Weisser: "The | QR | Code - Background and Visions - Description, History, Technology, Use, Dangers, Limits, Visions and Aesthetics of the" Fast Response "in the 21st Century". The | QR | Edition, Murnau am Staffelsee 2015, ISBN 978-3-95765-027-6 .

Web links

Commons : QR codes  - collection of images, videos and audio files

QR code generators

QR code decoder

Individual evidence

  1. ↑ European Patent Office: Masahiro Hara, Motoaki Watabe, Tadao Nojiri, Takayuki Nagaya, Yuji Uchiyama (Japan). Retrieved March 29, 2020 .
  2. ↑ QR Code Standardization | QR Code.com . Denso-wave.com. Retrieved April 23, 2009.
  3. ↑ Espacenet - Original document. Retrieved March 29, 2020 .
  4. ↑ AIM GLOBAL Online Store . Aimglobal.org. Archived from the original on June 21, 2010. Retrieved April 23, 2009.
  5. ↑ Information technology - Automatic identification and data capture techniques - Bar code symbology - QR Code . Retrieved November 24, 2011.
  6. ↑ Information technology - Automatic identification and data capture techniques - QR Code 2005 bar code symbology specification . Retrieved November 24, 2011.
  7. ^ Synchronization with Native Applications . NTT DoCoMo . Archived from the original on March 2, 2009. Retrieved February 17, 2009.
  8. ↑ Barcode Contents . In: zxing - A rough guide to standard encoding of information in barcodes . September 30, 2011. Retrieved November 23, 2011.
  9. ↑ How QR codes (and other 2D barcodes) work. Retrieved March 29, 2020 .
  10. ↑ Information capacity and versions of QR Code | QRcode.com | DENSO WAVE. Retrieved March 21, 2020 .
  11. ↑ a b QR Code Patent FAQ . Denso Wave. Retrieved February 11, 2015.
  12. ↑ N-Building QR code house facade . teradesign. Retrieved December 13, 2019.
  13. ↑ QR codes are also becoming increasingly popular in Europe (Toyota Tsusho ID Systems) . Archived from the original on July 31, 2011. Retrieved November 24, 2011.
  14. ↑ QR Code Patent FAQ . Denso Wave. Retrieved January 17, 2011.
  15. ↑ Cover of Spexx # 311 . Archived from the original on August 20, 2011. Retrieved November 24, 2011.
  16. ↑ WELT KOMPAKT introduces the 2D code . World online. November 9, 2007. Retrieved November 24, 2011.
  17. ↑ Logistics in the food industry . Retrieved December 1, 2011.
  18. ↑ QR codes at the BVG . Retrieved December 1, 2011.
  19. ↑ The EDEKA Südwest App . Retrieved December 1, 2011.
  20. ↑ ScanIT24 finds (almost) everything again - including the beloved pet. In: press box. Scanit24, April 4, 2013, accessed May 21, 2013 .
  21. ↑ QR Codes for Appstore . Archived from the original on November 23, 2011. Retrieved December 1, 2011.
  22. ↑ ANSM QR Code How-To Guide , Canadian Museum Reference for Technology.
  23. ↑ Interactive first day cover with QR code edition April 3rd, 2012 from the online mail order company M-ware® Electronics in Leipzig
  24. ↑ QR code sticker leads to the vehicle rescue card, commagazin.de of July 11, 2014, accessed on July 12, 2014
  25. ↑ Maik Jürß: New Mercedes-Benz Initiative: QR Code Can Save Lives - Quick Rescue of Accident Victims. In: Mercedes-Seite - Sicherheit , May 23, 2013. On the Mercedes website, accessed on February 4, 2019
  26. ↑ Virtual concert in the Holocaust memorial . ( Memento of October 29, 2013 in the Internet Archive ) In: BZ , August 5, 2013
  27. ↑ FOCUS Online: Iris Berben starts “interactive concert” at the Holocaust memorial. Retrieved March 29, 2020 .
  28. ↑ a b dpa : QR codes against counterfeiting , Münstersche Zeitung , December 21, 2012
  29. ↑ Jeevan M Meruga, William M Cross, P Stanley May, QuocAnh Luu, Grant A. Crawford, Jon J Kellar: Security printing of covert quick response codes using upconverting nanoparticle inks . In: Nanotechnology . 23, No. 39, 2012, ISSN  0957-4484 , p. 395201. doi : 10.1088 / 0957-4484 / 23/39/395201 .
  30. ^ Warning from the Better Business Bureau . Retrieved November 24, 2011.
  31. ↑ QR code dangers . Time online. September 21, 2011. Retrieved November 24, 2011.
  32. ↑ Android Trojans via QR code . Heise Security . October 2, 2011. Retrieved April 25, 2012.
  33. ↑ Android Trojan sends $ 6 SMS . Heise Security . September 11, 2010. Retrieved April 25, 2012.
  34. ^ Westfälische Nachrichten : Danger from pasted QR codes , Service, dpa , January 3, 2013
  35. ↑ QR Code Security (PDF; 355 kB) SBA Research , Vienna, Austria. Retrieved April 25, 2012.
  36. ↑ Russ Cox QR Art Codes . Retrieved May 5, 2012.
  37. ↑ Takashi Murakami and Louis Vuitton make QR codes fun again . Retrieved August 30, 2013.
  38. ↑ Denso Wave FAQs . Retrieved August 18, 2014.
  39. ↑ Micro QR Code Standardization | QR Code.com . Denso-wave.com. Retrieved April 17, 2012.
  40. ↑ DENSO WAVE Announces new QR Code® with canvas area in the center . Denso-wave.com. Retrieved January 8, 2015.
  41. ↑ Michael Weisser: Home
  42. ↑ Michael Weisser: Beginning of the experiments with the form and content of the QR code.
  43. ↑ M. Weisser 33! THINK! BANKS! Retrieved March 29, 2020 .
  44. ↑ focus.de: Interactive street art via QR code