Quick Response (QR) codes are one of the most familiar and recognizable types of 2D barcodes. Originally developed in 1994 by Masahiro Hara of Japanese company Denso Wave, QR Codes were designed to track vehicle components during the production process through high-speed scanning. Now, a variety of ISO/IEC standards cover the public domain use of QR codes including ISO/IEC 18004:2000, ISO/IEC 18004:2006 and ISO/IEC 18004:2015. QR Codes are also one of the only barcode types capable of encoding Japanese Kanji and Kana characters.
QR Codes are composed of three large squares at three corners of the barcode image and a fourth smaller square — or multiple squares — in the last corner which allows the barcode reader to determine image size, orientation, and viewing angle. Small dots located throughout the barcode are converted to binary and validated using an error-correcting algorithm. QR Codes also support multiple levels for error correction, with the tradeoff that as more information can be recovered, less information can be stored. These levels are:
- Level L (Low) — 7% of data can be recovered.
- Level M (Medium) — 15% of data can be recovered.
- Level Q (Quartile) — 25% of data can be recovered.
- Level H (High) — 30% of data can be recovered.