Two methodologies of bar code verification are TRADITIONAL and ANSI X3.182-1990 Bar Code Print Quality Guideline.

Traditional quality parameters are based on linear measurements of bar/space widths and reflectance values of background versus bar color. Parameters include: Encodation, Print Contrast Signal (PCS), Average Bar Deviation, Quiet Zone Dimensions, Wide to Narrow Ratios, Check Character Calculation.

1. Encodation verifies that the bar code pattern represents the correct series of characters.
2. Print Contrast Signal measures the contrast level between background and bars to be high enough for consistent reads.
3. Average Bar Deviation is the acceptable gain or loss allowed in the bar width.
4. Quiet Zones are the clear areas to the left and right of a barcode, required for the scanner to read.
5. Wide to Narrow Ratios define the relative width of the wide to narrow bars. Either 2:1, 2 1/2:1, or 3:1.
6. Check Characters are used as an algorithm that mathematically verifies a bar code value.

The American National Standards Institute (ANSI) has defined a set of quality parameters based on reflectance values as compared to an ideal "scan reflectance profile". The tests must be done with a contact scanning device, matching the scanner aperture to the width of the bar. For example a width range of 0.0131" to 0.0250 would require a 10 mil aperture.

ANSI defines four Pass/Fail Quality parameters: Edge Determination, Minimum Reflectance, Minimum Edge Contrast, Decode.

Edge Determination defines a global threshold between minimum and maximum reflectance. Global Threshold equals Reflectance (min) plus Symbol contrast divided by two. GT=Rm + SC/2

The Reflectance Minimum must be equal to or less than half of the Reflectance Maximum. Rmin =< Rmax

Edge Contrast Minimum equals the reflectance difference in the transition from a bar to a space. ECmin = Rsmin - Rbmax (worst pair)

Decode simply states the correct bar code value must be read a series of times without error.

In addition to the four Pass/Fail parameters, ANSI defines four Graded Qualities: Symbol Contrast, Modulation, Defects, Decodability.

Symbol Contrast equals Reflectance max minus Reflectance min. SC = Rmax - Rmin

Modulation equals Edge Contrast Minimum divided by Symbol Contrast. M = ECmin/SC

Defects are determined by the quantity and size of Voids and Spots. A Void is described by a bar with a hole inside. A spot is a space distorted by additional markings.

The graded quality of Decodability is defined by the measure of accuracy of the printed barcode against the appropriate reference decode algorithm. Different calculation methods are used for each type of symbology.