What is a Barcode Verifier?

If you're using barcodes as part of your business it's vital that those barcodes are printed to a high standard and that the data within the codes is correct.

International standards used to measure and define barcode print quality have been around since the early 1990s and the latest ISO/IEC standards (ISO 15416 and ISO 15415) lay down very specific criteria regarding linear (1D) and two dimensional (2D) barcode quality. These standards are used by all major industries and allow common parameters to be measured and used to describe the barcode quality regardless of the print process.

Scanning a barcode with a generic data capture device or mobile phone only confirms that the barcodes can be read by that device and not that the barcode is of an acceptable quality. This is why barcode verifiers are used to confirm that the barcode print quality and the data content meets certain industry standards in a precise and repeatable way.

Using common industry standards means that for a given barcode, two calibrated barcode verifiers should report the same barcode grading result within acceptable tolerances as laid down by those standards.

So what's the difference between a barcode verifier and a normal barcode scanner?

Barcode verifiers used to grade linear (1D) barcodes are built to comply with ISO 15426-1 whilst those used with two dimensional (2D) codes such as QR and Datamatrix, should comply with ISO 15426-2.

All certified barcode verifiers must comply with these standards which lay down rules governing the way the verifiers are built. So for example, the light source used to illuminate the barcode should be at a particular wavelength and angle in relation to the code and the aperture used by the light sensing equipment should be appropriate for the X dimension of the barcode. These standards ensure consistency across makes and models.

Unlike barcode verifiers, a simple barcode scanner is built to collect data without reporting any quality results. In many cases these scanners are designed to read even badly printed barcodes and many have advanced algorithms to achieve this. We can't assume that this will always be the case though which is why barcode quality is so important.

Scanning a barcode with a data capture device such as a basic barcode scanner or mobile phone does not guarantee quality.

What parameters are used to grade a barcode?

There are a number of parameters laid down in the ISO standards each of which returns a grading based either on a percentage of a pre-defined benchmark or as a simple PASS or FAIL. Symbol Contrast for example returns a grade (4.0 to 0.0) based on the difference between the maximum and minimum reflectance values within the barcode. Decode on the other hand simply returns a PASS (4.0) or FAIL (0.0) based on the decode algorithm for the barcode symbology being verified.

There are a number of common parameters used for both 1D and 2D barcodes and then additional parameters used for 2D codes only.

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.

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 of 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.

Are there different types of barcode verifier?

In the main barcode verifiers fall into two camps. Linear (1D) and two dimensional (2D) models. Many of the 2D models are able to verify both 1D and 2D barcodes and most models come with a piece of software that's loaded onto a PC, laptop or in some cases a Windows based tablet.

The software provides a clear and clean operator interface and shows a detailed colour coded analysis as well as a simple PASS or Fail result. The analysis allows the user to drill down into each verification parameter to see exactly why and where a barcode may be failing.

Some units are portable and provide a quick and simple method of confirming the barcode quality without the detailed graphical analysis. These units still conform to the relevant standards and are ideal for simple spot checks on the shop floor or in the warehouse.

Click on any of the models below for further details and specifications.

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.