Barcode
From Free net encyclopedia
Image:Wikipedia-barcode-128B.png Image:Datamatrix.png
A barcode (also bar code) is a machine-readable representation of information in a visual format on a surface. Originally barcodes stored data in the widths and spacings of printed parallel lines, but today they also come in patterns of dots, concentric circles, and hidden in images. Barcodes can be read by optical scanners called barcode readers or scanned from an image by special software. Barcodes are widely used to implement Auto ID Data Capture (AIDC) systems that improve the speed and accuracy of computer data entry.
While traditionally, barcodes encoding schemes represented just numbers, newer symbologies add new characters such as from the upper case alphabet to the complete ASCII character set and beyond. The drive to encode ever more information in combination with the space requirements of simple barcodes led to the development of matrix codes (a type of 2D barcode), which do not consist of bars but rather a grid of square cells. Stacked barcodes are a compromise between true 2D barcodes and linear codes, and are formed by taking a traditional linear symbology and placing it in an envelope that allows multiple rows.
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Usage
Since their invention in the last century, especially the UPC code, barcodes have slowly become an essential part of modern civilization. Their use is widespread and the technology behind barcodes is constantly improving. Some modern applications of barcodes include:
- Practically every item purchased from a grocery store, department store and mass merchandiser has a barcode on it. This greatly helps in keeping track of the large number of items in a store and also reduces instances of shoplifting. Since the adoption of barcodes, both consumers and retailers have profited from the savings generated.
- Rental car companies keep track of their cars by means of bar codes on the car bumper.
- Airlines track passenger luggage with barcodes, reducing the chance of loss.
- Recently, researchers have placed tiny bar codes on individual bees to track the insects' mating habits.
- NASA relies on bar codes to monitor the thousands of heat tiles that need to be replaced after every space shuttle trip.
- The movement of nuclear waste can be tracked easily with a bar-code inventory system.
- More recently, bar codes have even started appearing on humans. Fashion designers stamp bar codes on their models to help coordinate fashion shows. The codes store information about what outfits each model should be wearing and when they are due on the runway.
- In the late 1990's in Tokyo, there was a fad for temporary bar code shaped tattoos among high school girls.
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, the size of the quiet zone required to be before and after the barcode as well as the computation of a checksum.
Linear symbologies can be classified mainly by two properties:
- Continuous vs. discrete: Characters in continuous symbologies abut, with one character ending with a space and the next beginning with a bar, or vice versa. Characters in discrete symbologies begin and end with bars; the intercharacter space is ignored, as long as it is not wide enough to look like the code ends.
- Two-width vs. many-width: Bars and spaces in two-width symbologies are wide or narrow; how wide a wide bar is exactly has no significance as long as the symbology requirements for wide bars are adhered to (usually two to three times more wide than a narrow bar). Bars and spaces in many-width symbologies are all multiples of a basic width called the module; most such codes use four widths of 1, 2, 3 and 4 modules.
Stacked symbologies consist of a given linear symbology repeated vertically in multiple.
There are a large variety of 2-D symbologies. The most common are matrix codes, which feature square or dot-shaped modules arranged on a grid pattern. 2-D symbologies also come in a variety of other visual formats. Aside from circular patterns, there are several 2-D symbologies which employ steganography by hiding an array of different-sized or -shaped modules within a user-specified image (for example, DataGlyph).
Scanner/symbology interaction
Linear symbologies are optimized to be read by a laser scanner, which sweeps a beam of light across the barcode in a straight line, reading a slice of the barcode light-dark patterns.
Stacked symbologies are also optimized for laser scanning, with the laser making multiple passes across the barcode.
2-D symbologies cannot be read by a laser as there is typically no sweep pattern that can encompass the entire symbol. They must be scanned by a camera capture device.
Scanners (barcode readers)
Template:Main The earliest, and still the cheapest, bar code scanners are built from a fixed light and a single photosensor that is manually "scrubbed" across the barcode.
A later design, the "laser scanner," uses a polygonal mirror or galvanometer-mounted mirror to scan a laser across the barcode -- initially only in a straight line, but eventually in complicated patterns so the reader could read barcodes at any angle.
More recently, off-the-shelf digital cameras now have enough resolution to capture both 1D and 2D barcodes. Increasingly companies are looking to incorporate barcode scanning software into cameraphones. However, the camera phone optics are not well suited for standard codes that were designed for industrial dedicated scanners. As a result, new codes are being designed for mobile use such as color code and mCode.
Types of barcodes
Linear barcodes
| Symbology | Notes |
|---|---|
| Codablock | Stacked 1D barcodes. |
| Symbology | Notes |
|---|---|
| 3-DI | Developed by Lynn Ltd. |
| ArrayTag | From ArrayTech Systems. |
| Aztec Code | Designed by Andrew Longacre at Welch Allyn (now Hand Held Products). Public domain. |
| Small Aztec Code | Space conscious version of Aztec code. |
| Bullseye | This was the barcode tested in a Kroger store in Cincinnati. It used concentric bars. |
| Codablock | Stacked 1D barcodes. |
| Code 1 | Public domain. |
| Code 16K | Based on 1D Code 128. |
| Code 49 | Stacked 1D barcodes from Intermec Corp. |
| Color code | Mainly used for cell phones in Korea. |
| CP Code | From CP Tron, Inc. |
| DataGlyphs | From Xerox PARC. |
| Datamatrix | From RVSI Acuity CiMatrix. Now Public Domain. |
| Datastrip Code | From Datastrip, Inc. |
| Dot Code A | Designed for the unique identification of items. |
| HueCode | From Robot Design Associates. Uses greyscale or colour. |
| INTACTA.CODE | From INTACTA Technologies, Inc. |
| MaxiCode | Used by United Parcel Service. Now Public Domain |
| MiniCode | From Omniplanar, Inc. |
| PDF417 | Originated by Symbol Technologies Public Domain. The most common 2D barcode. |
| Micro PDF417 | Facilitates codes too small to be used in PDF417. |
| QR Code | De-facto standard for Japanese cell phones. Developed, patented and owned by TOYOTA subsidiary Denso Wave initially for car parts management. Can encode Japanese Kanji and Kana characters, music, images, URLs, emails. |
| Semacode | Open standard for picture cell phones |
| SmartCode | From InfoImaging Technologies. |
| Snowflake Code | From Marconi Data Systems, Inc. |
| ShotCode | Circular barcodes for camera phones by OP3. Orginally from High Energy Magic Ltd in name Spotcode. Before that probaply know as TRIPCode. |
| SuperCode | Public domain. |
| UltraCode | Black-and-white & colour versions. Public domain. Invented by Jeffrey Kaufman and Clive Hohberger. |
| VeriCode, VSCode | From Veritec, Inc. |
| WaterCode | High-density 2D Barcode(440bytes/cm2) From MarkAny Inc. |
See also
- Universal Product Code (UPC)
- Automated identification and data capture (AIDC)
- Semacode
- ISBN
- Inventory control system
- Supply Chain Management
- Barcode printer
- Barcode scanner
- Global Trade Item Number
- RFID
Further reading
- Automating Management Information Systems: Barcode Engineering and Implementation: Harry E. Burke, Thomson Learning, ISBN 0-442-20712-3
- Automating Management Information Systems: Principles of Barcode Applications: Harry E. Burke, Thomson Learning, ISBN 0442206674
- The Bar Code Book: Roger C. Palmer, Helmers Publishing, ISBN 0-911261-09-5, 386 pages
- The Bar Code Manual: Eugene F. Brighan, Thompson Learning, ISBN 0030161738
- Handbook of Bar Coding Systems: Harry E. Burke, Van Nostrand Reinhold Company, ISBN 0-422-21430-8, 219 pages
- Lines of Communication: Craig K. Harmon, Helmers Publishing, ISBN 0-911261-07-9, 425 pages
- Punched Cards to Bar Codes: Benjamin Nelson, Helmers Publishing, ISBN 0-911261-12-5, 434 pages
- Revolution at the Checkout Counter: The Explosion of the Bar Code: Stephen A. Brown, Harvard Univ Press, ISBN 0674767209
- QR-Codes and color codes for Mobile Phones and CRM: Gerhard Fasol, Eurotechnology Japan report, http://www.eurotechnology.com/store/qr-code/
External links
Patents
- Template:US patent - "Classifying apparatus and method"
History of barcodes
- Barcodes Sweep the World - A very detailed history (3300+ words).
- History of the Barcode by Stephen A. Brown
Barcode generators
- Barcode Generator
- PostScript-based barcode generator
- Online Barcode Generator for Linear, 2D and Composite Bar Codes
Standards
Barcode wikis and blogs
- How to Read 12 Digit UPC Barcodes
- Javapedia: Java bar code source code
- Wikipython: Python bar code source code
- Wiki Barcode Product Database public maintained info on all commercial items
How barcodes work and symbologies
- Complete List of Barcodes with samples
- How Stuff Works - UPC bar code
- Types of Barcodes - illustrated list
- Types of Barcodes - long list of symbologies
- Barcode Libraryda:Stregkode
de:Strichcode es:Código de barras fr:Lecteur de code-barres hr:Crtični kôd it:Codice a barre he:ברקוד hu:Vonalkód nl:Streepjescode ja:バーコード no:Strekkode pl:Kod kreskowy pt:Código de barras ro:Cod de bare ru:Штрихкод sl:Črtna koda fi:Viivakoodi sv:Streckkod th:บาร์โค้ด vi:Mã vạch zh:條碼