Why Doesn’t Your Barcode Scan?

Barcodes fail due to two main reasons:

1. Poor Image Quality: Scanners decode images. Inaccurate printing, lamination, shrink wrap and substrate characteristics can impact scanning
   

   Lamination

2. Incorrect Data Structure: Barcode data must be prefixed and parsed in compliance with the applicable standard.

ISO standards grade various print quality parameters:

• Contrast: Reflectance difference of bars (or squares) and spaces.
• Modulation: Uniformity of light and dark reflective values.
• Defects: Voids in bars, spots in spaces.
• Decodability: Accuracy of bar (or dot) and space width and location.
• Grid and axial accuracy of dot placement in 2D symbols.

Other factors that degrade barcode performance:

• Gain: Pigment spread causing reflectance variation. The ISO standard will soon include gain as a parameter.
• X Dimension: All barcodes have a minimum size. Smaller barcodes may be difficult or impossible to scan.
• Design Errors: Quiet zones encroached by graphics or text, or inaccurate barcode placement in a white zone.
• Data Entry Errors: Human-readable features like parentheses should not be encoded in the barcode.
• Abrasion and Wear: Storage and handling can degrade barcode images.
  

  Quiet Zone Violation

• Temperature Extremes: High heat can fade or obliterate images on heat-sensitive labels.
• Color: Scanning is defeated with certain colors.
• Non-flat Surfaces: Scanners must capture a full image of the barcode.
• Metal Substrates: Silvered, glossy, or brushed-metal substrates can cause scanning difficulties.

Key Takeaways:

• Track gain visually to identify potential issues.
• Test barcodes in their final form (e.g., after lamination or application on a cylinder).
• Use an ISO-compliant verifier for testing, not just a smartphone scanner.

Testing is faster and cheaper than recovering from a barcode disaster.

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