1 Scope
This Standard specifies the methodology for the measurement of print quality of bar code symbols.
This Standard applies to the measurement of print quality of bar code symbols. For the specific application fields have special national standards on bar code symbol inspection, the bar code symbols shall be inspected in accordance with such inspection standards.
2 Normative References
The following normative documents contain provisions which, through reference in this text, constitute provisions of this Standard. For dated references, subsequent amendments to, or revisions of, any of these publications do not apply. However, parties to agreements based on this Standard are encouraged to investigate the possibility of applying the most recent editions of the normative documents indicated below. For undated references, the latest edition of the normative document referred to applies.
GB/T 12905 Bar coding terminology
ISO 7724-2:1984 Paints and varnishes — Colorimetry — Part 2: Colour measurement.
3 Terms and Definitions
For the purposes of this Standard, the terms and definitions given in GB/T 12905 and the following apply.
3.1
Bar
A dark element corresponding to a region of a scan reflectance profile (3.16) below the global threshold.
3.2
Bar reflectance
The lowest reflectance value (3.16) of an individual bar element (3.1) in the scan reflectance profile of that element.
3.3
Decodability
The proportion of the available margin (between the ideal dimension of an element or combination of elements and the relevant reference threshold) that has not been consumed by the element or combination of elements, calculated for the element or combination of elements deviating most from its ideal dimension.
3.4
Symbol contrast
The difference between the maximum reflectance and minimum reflectance of scan reflectance profile (3.16).
3.5
Edge contrast
The difference between bar reflectance (3.2) and space reflectance (3.19) of two adjacent elements (includes quiet zone).
3.6
Element reflectance non-uniformity
The reflectance difference between the highest peak and the lowest valley in the scan reflectance profile (3.16) of an individual element (includes quiet zone).
3.7
Defects
The ratio of the maximum element reflectance non-uniformity to symbol contrast.
3.8
Global threshold
The reflectance level midway between the maximum and minimum reflectance values in a scan reflectance profile (3.16) used for the initial identification of bar (3.1) and space pairs (3.18).
3.9
Gloss
The propensity of a surface to reflect a proportion of incident light in a specular manner.
3.10
Inspection band
The band (usually from 10 % to 90 % of the height of a bar code symbol) across which measurements are taken (see Figure 2).
3.11
Measuring aperture
A circular opening which governs the effective sample area of the symbol, and the diameter of which at 1:1 magnification is equal to that of the sample area.
3.12
Modulation
The ratio of minimum edge contrast to symbol contrast.
3.13
(n, k) symbology
A class of bar code symbologies in which each symbol character is n modules in width and is composed of k bar (3.1) and space pairs (3.18).
