ISO/IEC 15416 (ANSI x3.182) Grading Parameters

The ANSI parameters section lists each of the nine ANSI parameters and gives a summary of the measurements based on all scans taken. For a review of the ANSI process given on each of your codes, check the ANSI Matrix for each code described below.

Note: Some of these parameters are average values over all of the scans, and the averages can skew or alter the apparent results.

The descriptions of each parameter explain what is measured in the case where a barcode is read and not read. When a code is not read, the scan is analyzed for apparent quiet zones and the bars and spaces in between are used for the ANSI analysis.

  1. EDGE: Edge Determination

    Checks if the edge between bar and space can be detected and no false bars or spaces appear due to “splitting” of bars or ink splattered into spaces. If at least one scan results in a decoded barcode, the EDGE value is the number of bars and spaces, not including quiet zones, in the code. If no scans result in a decoded barcode, the EDGE value shown is the number of bars and spaces found between quiet zones or apparent quiet zones on the scan on which the most bars and spaces were found. The Scan Reflectance Profile graph can also help in analyzing a code that cannot be decoded.

  2. Rl/RD: Minimum Reflectance

    Checks if the darkness of the bars is sufficient. The amount of light reflected by the bars (bar reflectance) must be less than half the light reflected by the spaces (space reflectance). The values shown are the light reflectance and the dark element reflectance separated by a slash. The light reflectance is the maximum reflectivity found in the scan (lightest or best space), and the dark reflectivity is the minimum reflectivity found in the scan (darkest or best bar). The requirement is for the minimum reflectivity to be no more than half the maximum reflectivity. If this requirement is met, the grade is A, otherwise it is F.

  3. SC: Symbol Contrast

    Measures the contrast between the brightest space and darkest bar. The result is assigned a letter grade of A, B, C, D, or F, with A being the highest contrast. The contrast is the difference between the maximum reflectivity (lightest or best space) and the minimum reflectivity (darkest or best bar). Note that Symbol Contrast is the difference between light and dark, and Rl/Rd above checks the ratio of these values.

    SC % Grade
    ≥ 70 A (4.0)
    ≥ 55 (but less than 70) B (3.0)
    ≥ 40 (but less than 55) C (2.0)
    ≥ 20 (but less than 40) D (1.0)
    < 20 F (0)

  4. MinEC: Minimum Edge Contrast

    Checks if the contrast between adjacent bars and spaces is high enough. If the difference between the light and dark elements is not significant, barcode readers fail to locate edges between bars and spaces.

    Note: MinEC finds the worst-case contrast difference between each bar to space transition, whereas symbol contrast finds the best-case difference at any point across the barcode.

  5. MOD: Modulation

    Modulation checks the edge contrast as a fraction of the overall or best case contrast measured in symbol contrast. Modulation is a measure of minimum edge contrast since most barcode readers employ adaptive thresholding circuits to detect transitions between bars and spaces. If all bars and spaces were the same brightness, the minimum edge contrast would be equivalent to the symbol contrast, resulting in 100% modulation. If some spaces are less bright than the brightest one, modulation is some fraction of the overall contrast. Modulation therefore measures the amount of available contrast that is manifested in the worst-case bar to space transition. The percentage is assigned a letter grade.

    Excessive ink spread or bar growth can result in low modulation because very narrow spaces appear to be filled in by the encroaching bars in the Scan Reflectance Profile.

    MOD % Grade
    ≥ 70 A (4.0)
    ≥ 60 (but less than 70) B (3.0)
    ≥ 50 (but less than 60) C (2.0)
    ≥ 40 (but less than 50) D (1.0)
    < 40 F (0)

  6. Def: Defects

    The worst-case change in reflectance within a single bar or space is a defect. The largest difference in reflectivity found in a single bar or space is measured as a percentage of the symbol contrast and assigned a letter grade. Defects measure breakups or voids within bars, ink spots in spaces, or even the grain of a substrate in spaces.

    Def % Grade
    ≤ 15 A (4.0)
    ≤ 20 (but greater than 15) B (3.0)
    ≤ 25 (but greater than 20) C (2.0)
    ≤ 30 (but greater than 25) D (1.0)
    > 30 F (0)

  7. DCD: Decode

    The widths of each bar and space are measured and used to interpret the data content of the barcode according to a specific mathematical formula appropriate for the barcode type. If the barcode cannot be decoded according to the formula, the accuracy of the bar and space widths are inadequate. The printout shows the number of scans decoded over the number of scans taken, for example 8/10 means 8 out of 10 scans decoded.

  8. DEC: Decodability

    Determines how accurate the bar and space widths are and how easily the widths can be determined. A perfectly accurate barcode has 100 percent decodability, but decodability as low as 25 percent is often acceptable. Decodability is the percentage of the overall tolerance range for a bar or space width that is not used up by inaccuracies.

    DEC % Grade
    ≥ 62 A (4.0)
    ≥ 50 (but less than 62) B (3.0)
    ≥ 37 (but less than 50) C (2.0)
    ≥ 25 (but less than 37) D (1.0)
    < 25 F (0)

  9. QZ: Quiet Zone

    Quiet Zone refers to a dedicated amount of blank space on the left and right of the barcode. Each symbology specifies a minimum quiet zone.