Barcode Verification versus Barcode Validation
Barcodes are used in virtually every business and manufacturing environment and form the basis for the vast majority of automatic data capture operations. The ability to scan barcodes quickly and accurately is vital and the use of Barcode Verification and Validation techniques helps to maintain barcode print quality and data integrity.
Barcode Verification versus Barcode Validation. What's the difference?
The terms Barcode Verification and Barcode Validation are often confused with the former being regularly used as a catch all term for any barcode checking procedure.
In reality, Barcode Verification refers to the process of confirming the print quality of a barcode to ISO/ANSI standards and where needed, confirms the format of the data content to particular application standards.
Barcode Validation is the process of confirming that the correct barcode information is being applied to the correct product, but not necessarily that the barcode meets a particular quality standard.
A poorly printed barcode may pass a validation test but could fail on verification.
Barcode verification is typically an offline process carried out by barcode verifiers built to the ISO/IEC 15426 standard. This standard ensures that every verifier regardless of make or model will provide a consistent quality grading.
If you grade the same barcode on any calibrated barcode verifier anywhere in the world, you should receive the same grading within certain pre-defined tolerances.
How does a barcode verifier report a grading result?
The most commonly referred to quality standard is the ANSI standard which returns a grading result in letters; A, B, C, D and F, where A is the highest quality and F the lowest. An ISO/IEC standard runs in parallel with the ANSI standard and returns a numeric result ranging from 4.0 to 0.0, where 4.0 is the highest and 0.0 the lowest.
The ISO/IEC and ANSI reporting systems use the same basic parameter set when grading barcodes and have a direct and fixed correlation to one another, so an ISO/IEC grade 4.0 barcode is also an ANSI grade A. The ISO/IEC methodology actually has a finer gradation in so far as it can be reported to a single decimal place, so by using this system a barcode grade ISO/IEC 3.5 is also an ANSI grade A, but not quite as good as an ISO/IEC grade 4.0.
A key showing the correlation between the two methodologies is shown below.
An example of a full barcode verification result could be: - 3.8/06/660 (A)
To break this result down: -
3.8 - The overall ISO grade.
06 – The verifier aperture that’s been used. This is important as the ISO/IEC standards dictate which size aperture should be used depending on the barcode X dimension (narrow bar width or cell size on a 2D code). In the old days this would be selected by the operator but today this is usually handled automatically.
660 – This represents the wavelength in nanometres of the light that’s been used to illuminate the code. Again this is important as the standards dictate the wavelength that can be used and it’s generally fixed for each verifier model.
A – This is the equivalent ANSI grade as explained above.
Which barcode verification standards are used?
The standards used for printed barcodes are ISO/IEC 15416 for 1D barcodes and ISO/IEC 15415 for 2D codes.
These standards grade the print quality of a barcode and measure a number of different parameters. The result of each parameter grading is reported using the same ISO/ANSI methodology returning a result of 4.0 to 0.0 and/or A to F.
The overall grade of a barcode is defined by the lowest of any of these individual parameters so a code with a contrast result of 1.7 (C) but all other parameters giving a grade 3.9 (A), will have an overall grade of 1.7 (C).
What grade do I need to pass?
For virtually all applications an ISO grade 1.5 (ANSI grade C) and above is considered a pass. One exception would be on some ITF14 barcodes particularly printed on fibreboard, where a grade D is considered a pass.
Barcode Application Standards
In addition to the ISO/ANSI standards, there are a number of barcode application standards that must be adhered to which will have an effect on the grading of a barcode. These standards are often industry and application specific and provide a pass or fail based on the specific requirements of that standard.
Examples of application standards are: -
- GS1 General Specifications (within which there are several individual standards) - LINK
- HIBC (used in healthcare) - LINK
- MIL-STD-130 (used by the United States DOD) - LINK
- MailMark (used by the UK Post Office) - LINK
You can think of these standards as being layered on top of the ISO/ANSI standards as they don’t replace them but rather incorporate them and add additional rules which in the main relate to the data content of the code itself. So for example, a well printed Datamatrix code may pass a basic ISO/IEC 15415 verification but when verified using the MailMark application standard could fail because the data isn’t encoded in the correct format.
In many cases the size of the barcode is important also so taking the MailMark standard as an example, The module size of Mailmark™ CMDMs must be in the range of 0.50 – 0.70mm and All data within the Royal Mail defined portion of the CMDM (all fields except customer content) shall comply with the C40 Basic Character set and C40 encodation scheme as described within ISO 16022.
Barcode Verifier Calibration
In order for a barcode verifier to accurately grade barcodes it's important that it's calibrated on a regular basis.
For most verifiers this is an operator procedure using the supplied standard GS1 Calibrated Conformance test card. These calibration cards are printed to a high standard and verified by one of a small number of barcode verifier 'judges' around the World. The cards are NIST traceable and go through a rigorous verification procedure themselves with the grading results being recorded on the card.
During the calibration procedure the verifier must report a grading for each parameter on the card within certain predefined tolerances. If any of the individual results fall outside of these tolerances then calibration will fail and remedial action required.
Barcode validation is the process of confirming that the data content within a barcode is correct.
Although barcode validation doesn't conform to the same strict industry standards as barcode verification, it should be seen as being at least as an important process.
The whole point of applying a barcode to a product or shipping case for instance is to identify those items through the use of automatic data capture equipment. If the data encoded within a barcode is incorrect then this data capture operation fails resulting in misplaced shipments, costly repackaging and in some cases renders the items unusable.
The Importance of Barcode Validation
In the worse case scenarios in healthcare for example, applying the wrong barcode to packaging can lead to incorrect pharmaceutical products being dispensed to patients with dire consequences. Luckily there are plenty of additional checks put in place in the pharmaceutical industry particularly with the adoption of the Falsified Medical Directive (FMD) and barcode validation is often at the center of quality assurance procedures.
In the retail sector, applying an incorrect barcode to a product often renders that product unsaleable. For the manufacturer this usually results in costly recalls and a hefty fine from the retailer in question.
How is Barcode Validation implemented?
Automatic barcode validation is usually found in the manufacturing industry where fixed mount barcode scanners are positioned on packaging lines in order to read each barcode as the products travel past.
A fully integrated barcode validation system should ideally include an operator control panel which allows the user to either select from a list of products or scan a code at the start of a production run in order to Teach the system which barcode is expected. If the unit reads a different barcode (a Wrong Read) or no barcode at all (a No Read), then an output should be triggered warning the operator and stopping the production line for example.