Edges: Bar and Space Transitions

As we’ve said before, barcode scanners work based on reflectivity and contrast. The messages encoded in linear barcodes are decoded on the basis of the scanner’s ability to detect reflective and contrast differences. In a pattern of lines and spaces, these critical differences are demarked by the edges—the places where the bar ends and the…

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Minimum Reflectance and Symbol Contrast

Minimum Reflectance and Symbol Contrast are tested by taking reflectance readings from the symbol—specifically the maximum reflectance value and the minimum reflectance value, and applying a calculation to those values. Minimum Reflectance is a Pass/Fail parameter A barcode image must have a minimum amount of reflective difference between the barcode and the background for the…

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