The Truth About Inline Barcode Verification

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There is no shortage of myths and beliefs circulating about inline barcode verification. There are two ways to deconstruct this technology:

  • Regulatory: ISO and industry applications such as UDI
  • Practicalities from use cases


The ISO standards for 1D barcodes and 2D symbols (ISO15416 and 15415 respectively) specify the attributes of the barcode which are to be measured, how each parameter is graded, and how a final symbol grade is determine and reported. The same standard applies to inline and offline or spot- checking verifiers.

It is important to note that most of the ISO parameters address issues of reflectivity. This is because reflectivity—or more accurately, reflective differences—are now scanners capture and decode the data contained in the barcode. This is true for all types of scanners: wands, lasers, linear or area CCD arrays and digital camera scanners.


The UDI Final Rule is representative of many industry applications: it defines barcode types (symbologies) and unique data formatting (parsing) schemes. Industry applications also detail how where the barcode should appear on a product or package. For example, a 1D barcode on an airline bag tag is present in both ladder and picket fence orientation to ensure it will work even if a printer pixel is burned out.


Barcode verification is important because of the job barcodes perform, from maintaining retail inventories to tracking medical devices, securing pharmaceutical supply chains, assuring accurate drug dosing at bedside and logging maintenance history of critical aircraft engine parts. Because of these practicalities, it is essential that barcodes are verified in their final form—as they appear when they are scanned in the retail store, surgical theater or aircraft maintenance facility.

It is also important that barcode verification is done in similar conditions to where they are scanned. Because of the wide variety of user environments, it is important for verification to avoid adding an additional variable to the process. In other words, to normalize and control the verification environment. This includes elimination of excess ambient light. While this might not match the environment in which the barcode is ultimately used, it establishes a reliable benchmark to predict barcode performance. It cannot be reasonably anticipated everywhere a barcode might be used, so testing it in a uniform environment proves that the barcode is viable under normative conditions.


The barcode on a medical device is not scanning right—the manufacture receives a chargeback that threatens not only the trading partner relationship but also the future of the company itself.

Scenario A: The medical device manufacturer “verifies” their barcodes with overhead, fixed mounted scanners running a verification software. They have archived millions of verification records showing passing grades on their barcodes. The installer “calibrated” the system several years ago using an offline verifier. Workspace lighting was replaced with high intensity LED’s. The inline system reads the barcodes so they must be compliant—but are they?

Customer has a problem with the barcodes on a lot or batch. Complains to the manufacturer who swears their barcodes are fine. Dissatisfied, the customer sues.

The case goes to court; the plaintiff’s expert witness points out that the inline verification system is not compliant because (a) there has been no regular recalibration and (b) variables such as ambient lighting influence the verification results.

The vendor doesn’t have a leg to stand on because “…but we’ve never had a problem…”is not a viable defense. They pay a 6 figure chargeback and lose the account.

Scenario B: The medical device manufacturer spot-checks barcodes with a certified, ISO conforming offline verifier. They have a verification report for the first and last, and additional reports from intervals during each print run.

Customer has a problem with the barcodes on a lot or batch. Complains to the manufacturer.

Changes to workspace lighting did not affect the verifier, which detected changes in the printing accuracy; continuous adjustments have maintained print accuracy. The offline verifier is recalibrated annually.

Customer is impressed and suspects problem could be with their scanners and has them checked against reference standard “golden” barcodes. Scanners are found to be out-of specification and are replaced.

Vendor earns a new level of trust and is recognized for their excellence.



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