QR code

Revision as of 22:53, 5 August 2023

QR codes (Quick Response) are a type of 2-dimensional bar code which is currently very popular. Originally designed for industrial use in tracking items as they move around a warehouse or factory, they are currently mainly used to provide hyperlinks in ads, articles, and signs which somebody with an appropriate reader (such as apps for a smartphone) can use to retrieve what is generally a URL linking into the Web, though other kinds of content can also be stored. SPARQCode is one of the methods used for standardizing the encoding of URLs and other specific kinds of data within a QR code. A company named DENSO-WAVE, which originally invented the codes, owns a trademark on the name "QR code", as well as various patents covering the technology, but allows free use of them as long as the standards are followed. They run the official QR Code website.

Software

• Review of barcode scanner apps
• Android app to read UPC and QR codes to look up product info/prices and other info coded or linked in bar codes
• Bar Code app (iOS)
• ZBar app (iOS)

Store data across multiple QR codes

• Structured Append feature (also Multi-part QR Code and Linked QR) - official way to split data across multiple QR codes, but not well supported and limited to 16 codes
  • Info from segno documentation
  • Discussion of how to use Structured Append
  • More discussion
• paperbackup- automatic ordering, data redundancy (can handle a missing QR code)
• paperbackup with reportlab backend
• Pawpyrus- generates a printable PDF of QR codes from any small-sized binary file
• qr-backup- converts file to a printable black-and-white pdf full of QR codes - offers redundancy, encryption, can restore data without program, up to 130KB/page
• Paperify- print files with QR codes (github, reddit post)
• Cyphar Paperback- Backups are encrypted, and the secret key is split into numerous "key shards" which can be stored separately (by different individuals)
• PyPaperBak- Python application to backup/restore binary files from paper storage
• QRBackup.sh- How to encode and decode a file backed up as a series of printed QR codes (github)
• papersave- Backup small important files to paper using standard tools, offers encryption and secret key splitting
• Barcode EPub- an EPUB reader that stores its data on paper (original article)
• asc2qr- specifically for ascii armor PGP keys
• TXQR (Transfer via QR)- transfer data via animated QR codes (github)
• qrloop- Encode a big binary blob to a loop of QR codes
• DisplaySocket.js- JavaScript library for sending data from one device to another using only a display and a camera
• qrcodetransfer- Java code to convert files to QR Codes and display them to another computer running the reader (archived homepage)
• QuickeR- Using video QR codes to transfer data
• AnimatedQRCodeReader (github)

Developer libraries

• ZBar bar code reader library: cross-platform
• zxing (Zebra Crossing) (barcode library for Java, ported to some other systems)
• barcode.php

Utilities

• Bar code generator: QR
• Online barcode generator (supports many different formats)
• Bar code creator

Other links and references

• QR code (Wikipedia)
• QRpedia (QR code with specially-formatted URL for language-independent Wikipedia links)
• Official QR site
• Reed Solomon Codes for Coders - Wikiversity tutorial
• Barcode contents
• WTF QR Codes
• Google Glass hacked by a simple QR code
• Mobile Web Tour at Walkway Over the Hudson (uses QR codes)
• Stamping Chinese banknotes with censorship-busting QR codes
• qrquine: QR code containing program code that reproduces itself
• Keep your data safe from the apocalypse in an Arctic mineshaft (uses QR codes)