Editing Barcode (section)

==Quality control and verification==
It is common for producers and users of bar codes to have a [[quality management system]] which includes [[verification and validation]] of bar codes.<ref>{{citation
 | last =David
 | first =H
 | title =Barcodes – Validation vs Verification in GS1
 | journal =Labeling News
 | date =28 November 2018
| url =http://www.labelingnews.com/2018/11/barcodes-validation-vs-verification-in-gs1/
 | access-date =6 June 2020
| archive-date =7 June 2020
| archive-url =https://web.archive.org/web/20200607173051/http://www.labelingnews.com/2018/11/barcodes-validation-vs-verification-in-gs1/
 | url-status =live
 }}</ref> Barcode verification examines scanability and the quality of the barcode in comparison to industry standards and specifications.<ref>{{cite web
 |url= https://www.bar-code.com/verifiers/LaymansGuidetoANSI.pdf
 |title= Layman's Guide to ANSI, CEN, and ISO Barcode Print Quality Documents
 |publisher= Association for Automatic Identification and Data Capture Technologies (AIM)
 |date= 2002
 |access-date= 23 November 2017
|archive-date= 10 September 2016
|archive-url= https://web.archive.org/web/20160910162109/http://www.bar-code.com/verifiers/LaymansGuidetoANSI.pdf
 |url-status= dead
 }}</ref> Barcode verifiers are primarily used by businesses that print and use barcodes. Any trading partner in the [[supply chain]] can test barcode quality. It is important to verify a barcode to ensure that any reader in the supply chain can successfully interpret a barcode with a low error rate. Retailers levy large penalties for non-compliant barcodes. These chargebacks can reduce a manufacturer's revenue by 2% to 10%.<ref>{{cite journal|last=Zieger |first=Anne |title=Retailer chargebacks: is there an upside? Retailer compliance initiatives can lead to efficiency |journal=Frontline Solutions |date=October 2003 |url=http://findarticles.com/p/articles/mi_m0DIS/is_10_4/ai_109518393/ |archive-url=https://archive.today/20120708192857/http://findarticles.com/p/articles/mi_m0DIS/is_10_4/ai_109518393/ |url-status=dead |archive-date=8 July 2012}}</ref>

A barcode verifier works the way a reader does, but instead of simply decoding a barcode, a verifier performs a series of tests. For linear barcodes these tests are:
* Edge contrast (EC)<ref name=":3"/>
**The difference between the space reflectance (Rs) and adjoining bar reflectance (Rb). EC=Rs-Rb
* Minimum bar reflectance (Rb)<ref name=":3"/>
**The smallest reflectance value in a bar.
* Minimum space reflectance (Rs)<ref name=":3"/>
**The smallest reflectance value in a space.
*Symbol contrast (SC)<ref name=":3">{{Cite web|url=https://www.expresscorp.com/Barcode-Glossary|title=Barcode Glossary {{!}} Express|last=Corp|first=Express|website=Express Corp|language=en|access-date=11 December 2019|archive-date=11 December 2019|archive-url=https://web.archive.org/web/20191211231342/https://www.expresscorp.com/Barcode-Glossary|url-status=live}}</ref>
**Symbol contrast is the difference in reflectance values of the lightest space (including the quiet zone) and the darkest bar of the symbol. The greater the difference, the higher the grade. The parameter is graded as either A, B, C, D, or F. SC=Rmax-Rmin
* Minimum edge contrast (ECmin)<ref name=":3"/>
**The difference between the space reflectance (Rs) and adjoining bar reflectance (Rb). EC=Rs-Rb
* Modulation (MOD)<ref name=":3"/>
**The parameter is graded either A, B, C, D, or F. This grade is based on the relationship between minimum edge contrast (ECmin) and symbol contrast (SC). MOD=ECmin/SC The greater the difference between minimum edge contrast and symbol contrast, the lower the grade. Scanners and verifiers perceive the narrower bars and spaces to have less intensity than wider bars and spaces; the comparison of the lesser intensity of narrow elements to the wide elements is called modulation. This condition is affected by aperture size.
*Inter-character gap<ref name=":3"/>
**In discrete barcodes, the space that disconnects the two contiguous characters. When present, inter-character gaps are considered spaces (elements) for purposes of edge determination and reflectance parameter grades.
* Defects
* Decode<ref name=":3"/>
**Extracting the information which has been encoded in a bar code symbol.
* Decodability<ref name=":3"/>
**Can be graded as A, B, C, D, or F. The Decodability grade indicates the amount of error in the width of the most deviant element in the symbol. The less deviation in the symbology, the higher the grade. Decodability is a measure of print accuracy using the symbology reference decode algorithm.

2D matrix symbols look at the parameters:
* Symbol contrast<ref name=":3"/>
* Modulation<ref name=":3"/>
* Decode<ref name=":3" />
* Unused error correction
* Fixed (finder) pattern damage
* Grid non-uniformity
* Axial non-uniformity<ref>{{cite journal|author=Bar Code Verification Best Practice work team|title=GS1 DataMatrix: An introduction and technical overview of the most advanced GS1 Application Identifiers compliant symbology|journal=Global Standards 1|date=May 2010|volume=1|issue=17|pages=34–36|url=http://www.gs1.org/docs/barcodes/GS1_DataMatrix_Introduction_and_technical_overview.pdf|access-date=2 August 2011| archive-url= https://web.archive.org/web/20110720135555/http://www.gs1.org/docs/barcodes/GS1_DataMatrix_Introduction_and_technical_overview.pdf| archive-date= 20 July 2011 | url-status= live}}</ref>

Depending on the parameter, each [[ANSI]] test is graded from 0.0 to 4.0 (F to A), or given a pass or fail mark. Each grade is determined by analyzing the [[scan reflectance profile]] (SRP), an analog graph of a single scan line across the entire symbol. The lowest of the 8 grades is the scan grade, and the overall ISO symbol grade is the average of the individual scan grades. For most applications a 2.5 (C) is the minimal acceptable symbol grade.<ref>{{cite journal|author=GS1 Bar Code Verification Best Practice work team|title=GS1 Bar Code Verification for Linear Symbols|journal=Global Standards 1|volume=4|date=May 2009|issue=3|pages=23–32|url=http://www.gs1.org/docs/barcodes/GS1_Bar_Code_Verification.pdf|access-date=2 August 2011|archive-date=27 September 2011|archive-url=https://web.archive.org/web/20110927053101/http://www.gs1.org/docs/barcodes/GS1_Bar_Code_Verification.pdf|url-status=live}}</ref>

Compared with a reader, a verifier measures a barcode's optical characteristics to international and industry standards. The measurement must be repeatable and consistent. Doing so requires constant conditions such as distance, illumination angle, sensor angle and verifier [[aperture]]. Based on the verification results, the production process can be adjusted to print higher quality barcodes that will scan down the supply chain.

Bar code validation may include evaluations after use (and abuse) testing such as sunlight, abrasion, impact, moisture, etc.<ref>{{citation
| last =Garner
| first =J
 | title =Results of Data Matrix Barcode Testing for Field Applications
| publisher =Oak Ridge National Laboratory
 | date = 2019
 | url = https://www.osti.gov/servlets/purl/1524857
 | access-date =6 June 2020
}}</ref>

===Barcode verifier standards===
Barcode verifier standards are defined by the [[International Organization for Standardization]] (ISO), in ISO/IEC 15426-1 (linear) or ISO/IEC 15426-2 (2D).{{citation needed|date=February 2020}} The current international barcode quality specification is ISO/IEC 15416 (linear) and ISO/IEC 15415 (2D).{{citation needed|date=February 2020}} The [[European Standard]] EN 1635 has been withdrawn and replaced by ISO/IEC 15416. The original U.S. barcode quality specification was [[ANSI]] X3.182. (UPCs used in the US – ANSI/UCC5).{{citation needed|date=February 2020}} As of 2011 the ISO workgroup JTC1 SC31 was developing a [[Direct part marking|Direct Part Marking (DPM)]] quality standard: ISO/IEC TR 29158.<ref>{{cite web |url=http://www.iso.org/iso/iso_technical_committee.html?commid=45332 |title=Technical committees – JTC 1/SC 31 – Automatic identification and data capture techniques |date=4 December 2008 |publisher=ISO |access-date=28 November 2011 |archive-date=18 October 2011 |archive-url=https://web.archive.org/web/20111018171042/http://www.iso.org/iso/iso_technical_committee.html?commid=45332 |url-status=live }}</ref>