Grid nonuniformity measures the largest deviation of the grid centers from their ideal theoretical position, as determined by the reference decode algorithm. The measurements are expressed as a fraction of the width of the symbol under test. The following image illustrates grid nonuniformity by comparing an actual symbol under test with the border of the ideal grid position.

  1. Symbol under test
  2. Ideal grid position outline

The following list shows how grid non-uniformity is graded.

  • A (4.0) if grid non uniformity ≤ 0.38
  • B (3.0) if grid non uniformity ≤ 0.50
  • C (2.0) if grid non uniformity ≤ 0.63
  • D (1.0) if grid non uniformity ≤ 0.75
  • F (0.0) if grid non uniformity > 0.75

The following figure shows a Data Matrix code with a grid nonuniformity score of 1.88, which returns a grade of F.