Barcode Verification Guide

Why is Barcode quality important?

Barcoding has transformed value chain management over the last twenty years, and the ability to capture data automatically at every significant point in the chain enables faster and more efficient management.

Printing a good quality barcode that conforms to GS1 standards may cost more than printing unscannable symbols, but the benefits outweigh the costs.

The accuracy of barcodes remains fundamentally important because when a barcode fails to scan it adds cost to the trading process. At best data has to be keyed in manually, and at worst customers may reject a complete consignment of goods, resulting in lost sales and possible financial penalties.

All barcodes represent data in a machine readable form. The different widths of bars and spaces in a barcode symbol represent different numbers or letters which can be decoded by a scanner. The data is then sent back to the appropriate computer system where it is recorded and used to prompt further action. This action can be anything from displaying a item description and price – as in a supermarket checkout or registering the arrival of a pallet of goods in a warehouse. The importance on keeping this code readable for all situations is an ever growing problem.

So how do you ensure your Barcodes read?

We often hear from customers who use a standard barcode scanner to read their barcodes and use the success of the read as a level of testing. The issue here is that this test is only as good as the device used and it does not provide any real verification that would ensure that other scanners could also read these codes.

We sell inexpensive barcode readers that will read extremely poor codes – but that won’t help you in the testing of yours!

We have supplied small battery operated barcode readers that customers have used for this purpose – however, they found that barcodes that initially read with these devices went out only to fail in the real world – a very expensive mistake.

Watch this video and see the difference between Barcode Scanners and Barcode Verifiers:

The only real test that provides you accurate and informative information on the print quality of your barcodes is to use a Barcode Verifier. The Verifier will tell you exactly what is the problem is and what needs to be improved.

Be Warned – there are lots of old verifiers out there that are not worth the money they cost and are next to useless as verifiers! The Verifier used must be an ISO grade unit – as this ensures that the quality of the Verifier and its method of testing criteria applied is of an industry standard. Verifiers must meet the stringent requirements of the international specification ISO/IEC 15426-1 are able to measure the contrast of a printed barcode, and they must check that particular colour combinations are scannable, as well as a host of other tests parameters are met.

Prior to the ISO standards being introduced – most verifiers manufactured all gave different results – even when they scanned the same code! This was because they were all built to different quality standards and used variations of verification methods. Once the ISO standards were introduced, most of these brands vanished overnight as they simply could not comply with these quality standards.

Current Range of ISO Grade Bar Code Verifiers

The Importance of Verification The ease with which a barcode can be read depends on how well the code has been printed, and on certain parameters of the scanner. Specifications lay down the ideal dimensions and methods of production of codes, but it is not always possible to adhere to the ideal conditions. Therefore, in practice, barcodes can be produced that are not perfect and which may or may not scan successfully. In addition, there are other problems that can occur in the printing or production process which may contribute to the difficulty of scanning.

So how does Verification work – see this video for a full example of GS1 Verification at work:

So how can the chances of a code scanning be assessed?

Traditionally there have been a few ways of trying to ensure that a code will scan. The retail code system, which is organised worldwide by the GS1 organisation, has relied on accurate film masters to be used in the creation of printing plates to attain the quality required. However, not all codes are printed on large presses, and these other printing processes have various limitations and potential error conditions.

ISO Verification equipment has been around for some years to assess the dimensional accuracy of printed codes. Although these devices have proved extremely useful, some units available may not fully explain why a code will or will not read. When buying a Verifier it is important to ensure the unit is user-friendly and that the results can be understood! Make sure that the unit is ISO compliant and that when the results are produced you can understand what they mean! Ask for a demonstration and review the verification report – remember that this is an extremely valuable tool and these reports can be sent with your printed labels as proof of compliance.

Verifying Label printed Barcodes – see the ease of introducing this system into your business: 

New Verification Standards (ISO)

In order to create a universal international standard for verification equipment that assesses the printed barcode from the point of view of scanning and decoding rather than the dimensional accuracy of the ink on the paper, the American National Standards Institute (ANSI) has developed a new method of analysing the printed code.

This method, which has already been adopted in the European Community (CEN) and has now of become a world standard (ISO), is far more detailed than the previous methods of verification, but it does reveal more possible problems with a printed barcode.

In particular, it highlights problems that are associated with printers used for generating bar-coded labels, where printer machinery faults may cause unwanted gaps, holes or specks of ink in places where smooth coverage of ink or absence of ink should exist. It also highlights the problems that can occur when mixtures of colours are used, such as on magazine covers.

Some verifiers uses the ANSI and CEN grading system which takes into account seven main parameters:


Minimum Reflectance


Symbol Contrast


Minimum Edge Contrast









For each scan, the lowest single grade of these seven (being the weakest link in the chain) becomes the overall grade. After the recommended ten scans have been taken, the results are averaged, and each parameter, including the overall grade, is graded A-F (ANSI) or 4-0 (CEN).

The required pass grade for most major retailers is a grade 2 (C) or above for all bar codes, with the exception of those printed directly onto corrugated fibreboard, for which a Grade 1 (D) is normally acceptable.

In addition to the above tests performed on the printing quality of the Barcode, there are also some physical requirements that affect the overall quality:


Adequate light margins or quiet zones must be provided to the left and right of each bar code.


The target size is usually 100% but the standards allow a range between 80% and 200%. However, keep them in the 80% to 120% magnification range if print quality allows. When printing barcodes smaller than 100% remember that the printing tolerances are much tighter, and you must use high-quality printing processes. It is not always possible to improve the quality of the printing process so tests must be carried out before committing to a particular size of the symbol. The Barcode Verifier provides this information.


The bars of the codes must also not be shortened in height (truncated) unless the product’s size makes this absolutely necessary - a size template is available for the various sizes to check these dimensions.

Common Barcode Quality Problems to look out for:


The light margins required for each barcode are not large enough. This can also occur when the barcode is printed too close to the label edge.


The barcodes are shortened below their standard height (known as truncation).


Missing bars or horizontal white lines crossing the barcode because of faulty print heads used for on-demand printing.


Choosing incorrect colour combinations, often orange or red bars on a pale background, which will not scan. Reversed out images, where the bars are white against a coloured background, are again not scannable.


Using transparent or semi-transparent substrates, such as glass or plastic, and hoping that the contents will provide a suitable background colour either, for the bars or the spaces.


Printing barcodes that are either too large or too small. Incorrect adjustment for ink spread (the bar width reduction). The printed bars are out of specification, either being too narrow or too wide.


Placing labels too close to vertical corners or wrapping them around corners so that the barcodes are too close to the edge.


Printing barcodes onto the film which is distorted as it is used as shrink wrap.

Intermax has been involved with barcode verification for over a decade and has a strong alliance with GS1. If you need any advice in this area or would like to consider buying one of these devices, please do not hesitate to call one of our technicians or simply contact us.

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