Why Did My Code Fail the Decode Parameter Quality?


The first step in the barcode verification process is to check that the code can be decoded. Since decode is a pass or fail quality parameter failing for decode can often feel like a dead end. Traditional verifiers will test for decode first and upon failure does not continue with the remaining verification grading process. This leaves users with an “F” grade but no explanation of why. A failure for decode really means that the code was not printed or marked well enough to be decoded by the standard reference decode algorithm. 

What is Standard Code Reference Algorithm? 

The standard reference decode algorithm is the algorithm listed in the ISO standard for each symbology type. It is the most simplistic decode algorithm for each symbology. A verifier uses it as the first test to ensure a code can be read. The main purpose of a verifier is to ensure that the majority of barcode readers or barcode scanners can decode the code. One way it does that is by confirming a code can be read without a fancy decode algorithm.

Presumably an inexpensive barcode reader manufacturer would not spend time and money to develop their own decode algorithms and instead use the standard reference decode algorithm in their scanners. Most barcode readers brands strive to develop their own proprietary powerful decode algorithms that can handle damaged or defective codes. This is their greatest asset against other barcode readers manufacturers and what they will use as a selling point for customers to choose their brand over another.  


Do I Need a Powerful Reader?

Working with a powerful reader has many benefits, but when your easily read codes leave and land at a facility that doesn’t have powerful barcode readers problems will arise. For this reason, many manufacturers turn to verification. Since suddenly, codes that could be read easily now cannot be read at all. Companies will argue over if the issue with the code or the reader. Manufacturers and customers can go back and forth debating until the end of time unless a barcode verifier is used. Verifiers not only calculated a quality grade for a barcode, but they also generate a quality report. That report is proof that a code can be read, and the data is decoded.  

What to Try When Your Barcode Is Failing to Decode

  • 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.

Cognex verifiers, will provide quality parameter grading even if a code fails for decode giving users an idea of where to start to improve code quality. For more information on barcode verification products at Cognex please visit, http://www.cognex.com/barcode-verifiers

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