Written by John Nachtrieb
Once again we have evidence that the only thing that doesn’t change is change itself. Recently there has been an update to the ISO 15416 specification for 1D or linear barcodes, and it could make a difference in the final verification grade for a barcode. Two recent changes have been made and updated in the ISO 15416 specification.
The first recent change seems simple enough—the reported grades for Symbol Contrast, Modulation, Defects and Decodability will now be measured and reported to one decimal place. Decode, Minimum Reflectance and Minimum Edge Contrast will continue to be reported as Pass/Fail (either 4.0 or 0.0) parameters. Yes this is the “fine print” but it can make the difference between a passing or failing grade when a parameter is marginally passing or failing.
The second recent change to ISO 15416 is a bit more subtle. It effects how the parameter Defects is calculated, or more precisely where the defect is located in the barcode and how it impacts the grade for this parameter. Without going into the decode mathematics, here is what has changed:
- The former decode calculation resulted in a large error being reported when the defect is near the edge of a bar or space—even when the error had a relatively small effect on reflectance.
- The successor calculation corrects for the exaggeration in the old methodology and will improve grades for this type of defect.
When two verifiers don’t agree on grading it can be a vexing problem. Which one is truthful–are either of them truthful? How do I settle the disagreement? Where do I begin? With these changes in the ISO specification, one can see how important it is for a verifier to be diligently updated: changes are published not only to the manufacturer’s software but also to the ISO parameters. Re-calibrating a verifier for reflectivity on a regular basis is not enough to ensure that your verifier is up to date. Go to the manufacturer’s website or contact your reseller to check if there have been software updates.
Known updates to the ISO specification are an opportunity to substantiate whether or not your verifier is truly ISO compliant. Some data sheets are more oriented toward marketing than honest reporting of technical information. If your verifier brand “never requires calibration” that is a failing marketed as a feature. Due to design considerations, it is nearly impossible and/or very expensive to update some verifiers, so the manufacturers may be less than eager to report ISO updates that should result in verifier updates. Whether you are researching the purchase of a new verifier or inquiring about a verifier you already own, ask how ISO updates and software updates are done. Listen for—and insist on–a simple, direct answer.
About the Author
Mr. Nachtrieb has 30+ years of hands-on experience in barcode technology. His team imaged the film master for the first commercially scanned barcode in North America (1974). His specialty is barcode quality. He created and hosts a highly customized barcode quality seminar which has been presented to 100’s of companies, reaching thousands of quality-concerned people, helping them to avoid barcode problems and manage barcode-related risk.
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