Meaning
Image quality metrics determine the legibility of a two-dimensional code by comparing the light intensity of its elements. Achieving sufficient cell contrast requires a significant difference in reflectance between the dark modules and the light background of a symbol. This measurement ensures that a scanner can distinguish the data-carrying cells from the surrounding quiet zone.
Signal Strength
Reflectance values are captured across the entire surface of the mark. If the cell contrast falls below the threshold defined by ISO 15415, the grade of the code drops.
Marking Method
Laser etching or thermal printing creates the physical changes on the substrate that define the symbol. The choice of material affects the cell contrast because porous surfaces absorb more ink and reduce the brightness of the light cells. Adjusting the power of a laser can darken the cells to improve the signal without damaging the underlying component.
Consistent application of the marking energy ensures that every unit remains within the specified tolerance for readability.
Distribution Assurance
Retailers often include minimum grading requirements in their vendor compliance manuals to prevent delays in the supply chain. A symbol with poor cell contrast will cause failures in automated sorting centers where speed is essential. Suppliers who fail to monitor this metric risk financial penalties and the return of non-compliant inventory.
Reliable cell contrast ensures that the data remains accessible throughout the life of the product.
