Barcode symbologies

• The mapping between messages and barcodes is called a symbology.
• The specification of a symbology includes the encoding of the single digits/characters of the message, as well as the start and stop markers into bars and space, and the computation of a checksum.
• There are generally four types of barcode symbologies: Discrete, Continuous, Two-width and Multiple-width.

Discrete

• A discrete symbology is one where each and every character encoded in the symbol may be interpreted individually without respect to the rest of the barcode.
• Individual characters are separated by some amount of inter-character spacing.

Continious

• A continuous symbology is one in which the individual characters of the symbology cannot be interpreted by themselves.
• This is due to the fact that characters start with a bar and end with a space.
• The final space is "terminated" by the starting bar of the next character.
• The last space of the last data character is terminated by the termination bar.

Two-Width

• A Two-width symbology has spaces and bars that are either wide or narrow.
• This has the benefit of simplicity-once it is determine how wide a "narrow" bar or space is, anything over a certain width can be considered wide. Example is Code 39 symbology.
• Below figure 1 and 2 represents the width of bars.

Multiple-Width

• A Multiple-Width symbology is one which has bars and spaces that may be of 3 or more widths. Example is Code 128 symbology.
• Below figure 1, 2, 3 and 4 represents the different widths of bars.

Types of barcodes

Linear barcodes

• A first generation, "one dimensional" barcode that is made up of lines and spaces of various widths that create specific patterns.

Example	Symbology	Continuous or Discrete	Bar widths	Uses
	Code 25 – Interleaved 2 of 5	Continuous	Two	Wholesale, libraries International standard ISO/IEC 16390
	Code 11	Discrete	Two	Telephones (out of date)
	Farmacode or Code 32	Discrete	Two	Italian pharmacode – use Code 39 (no international standard available)
	Code 39	Discrete	Two	Various – international standard ISO/IEC 16388
	Code 49	Continuous	Many	Various
	Code 128	Continuous	Many	Various – International Standard ISO/IEC 15417
	DX film edge barcode	Neither	Tall/short	Color print film
	EAN 2	Continuous	Many	Addon code (magazines), GS1-approved – not an own symbology – to be used only with an EAN/UPC according to ISO/IEC 15420
	EAN 5	Continuous	Many	Addon code (books), GS1-approved – not an own symbology – to be used only with an EAN/UPC according to ISO/IEC 15420
	EAN-13	Continuous	Many	Worldwide retail, GS1-approved – International Standard ISO/IEC 15420
	Pharmacode	Discrete	Two	Pharmaceutical packaging (no international standard available)
	Universal Product Code	Continuous	Many	Worldwide retail, GS1-approved – International Standard ISO/IEC 15420

Matrix (2D) barcodes

• A Mat rix code,also termed a 2D barcode or simply a 2D code, is a two-dimensional way to represent information. It is similar to a linear (1-dimensional) barcode, but can represent more data per unit area.

Example	Name	Notes
	Aztec Code	Designed by Andrew Longacre at Welch Allyn (now Honeywell Scanning and Mobility). Public domain. – International Standard: ISO/IEC 24778
	CrontoSign	CrontoSign (also called photoTAN) is a visual cryptogram containing encrypted order data and a one-time-use TAN.
	Data Matrix	From Microscan Systems, formerly RVSI Acuity CiMatrix/Siemens. Public domain. Increasingly used throughout the United States. Single segment Data Matrix is also termed. International Standard: ISO/IEC 16022.
	High Capacity Color Barcode	Developed by Microsoft; licensed by ISAN-IA.
	Han Xin Barcode	Barcode designed to encode Chinese characters introduced by Association for Automatic Identification and Mobility in 2011.
	NexCode	NexCode is developed and patented by S5 Systems.
	PDF417	Originated by Symbol Technologies. Public Domain. International Standard: ISO/IEC 15438
	Qode	American proprietary and patented 2D barcode from NeoMedia Technologies, Inc.
	QR code	Initially developed, patented and owned by Toyota subsidiary Denso Wave for car parts management; they have chosen not to exercise their patent rights. Can encode Japanese Kanji and Kana characters, music, images, URLs, emails. De facto standard for Japanese cell phones. Also used with BlackBerry Messenger to pickup contacts rather than using a PIN code. These codes are also the most frequently used type to scan with smartphones. Public Domain. International Standard: ISO/IEC 18004
	SPARQCode	QR code encoding standard from MSKYNET, Inc.