Key Takeaways
Some important things to know about decoding failures and barcode quality include:
- The standard reference decode algorithm ensures broad compatibility across barcode readers.
- Common issues stem from incorrect aperture, lighting, or ink quality.
- Practical fixes include adjusting focus, cleaning print heads, or changing substrates.
When barcodes can’t be read, it can be hard to figure out if the scanner or code is at fault. Many manufacturers turn to barcode verifiers as a result. Verifiers calculate quality grades for barcodes and generate a quality report for every code verified. Those reports are proof that codes can be read, and data can be decoded.
The first test in verification is simply to see if a barcode can be decoded. If it can’t, that parameter gets an "F" grade and the verifier stops the grading process. The “F” grade is shown to the user, but there’s no explanation provided. An “F” grade means the code was not printed or marked well enough to be decoded by the standard reference decode algorithm.
What is the standard reference decode algorithm?
Generally, barcode reader manufacturers save time and money when developing their own decode algorithms by using the standard reference decode. In contrast, other manufacturers tend to develop proprietary, powerful decoding algorithms to handle damaged or defective codes. Due to differences in readers, testing with the standard reference decode algorithm ensures the broadest range of barcode readers can decode your barcodes.
What to try when your barcode is failing the decode quality parameter
- Are you using the correct aperture?
- Are you using the right ISO standard?
- Are you using the right lighting angle?
- Is the symbology enabled?
- Is the symbol "mirrored"?
- Is the camera in focus?
- Is the code in the center of the FOV?
- Do the cell sizes look proportionate to one another?
- Are the edges of the cell crisp?
- Are all the components of the finder pattern present?
- Is the inkjet nozzle blocked?
- Is the thermal element faulty?
- Try using less ink or a different kind of ink.
- Change paper or substrate.
- Adjust artwork to accommodate known growth.
- Clean print head.
- Reduce thermal or laser heat.
Unlike other barcode verifiers on the market, Cognex barcode verifiers provide quality parameter grading. This is true even if a Data Matrix or QR code fails the decode quality parameter – helping users know how to start improving code quality.