Meaning
Technical metric representing the lowest amount of light reflected from the dark bars of a barcode. Measuring minimum reflectance rmin is a critical step in determining the contrast ratio between the bars and the light spaces. This parameter is no longer relevant once the scan has been successfully decoded by the terminal software.
Optical Contrast
Scanners rely on the difference between the darkest and lightest parts of the symbol to decode the information. If the minimum reflectance rmin is too high, the bars appear gray to the laser or camera, causing a read error. This often happens when the ink density is insufficient or the substrate is too translucent.
Grading Standard
ISO standards for barcode quality use this value as one of the primary parameters for the final grade. A failure in minimum reflectance rmin can lead to a grade of F, even if the barcode geometry is perfect. Quality control teams monitor this during the print run to ensure the ink levels remain consistent and the rollers are clean.
Economic Consequence
Labels that do not meet the specification for minimum reflectance rmin are often rejected by high-speed sorting facilities. The cost of reprinting and reshipping the goods can be substantial for the manufacturer. In a contract, the buyer may specify the exact densitometer readings required for acceptance at the distribution center.
Maintaining a low reflectance value in the dark elements is necessary for global supply chain interoperability.
