ISO IEC 15416 pdf download

ISO IEC 15416 pdf download Information technology — Automatic identification and data capture techniques — Bar code print quality test specification — Linear symbols
4 Symbols and abbreviated terms
4.1 Abbreviations
EC: Edge contrast
EC min : Minimum value of EC
ERN: Element reflectance non-uniformity
ERN max : Maximum value of ERN
GT: Global threshold
MOD: Modulation
PCS: Print contrast signal
RT: Reference threshold
SC: Symbol contrast
SRD: Static reflectance difference
4.2 Symbols
A: Average achieved width of element or element combinations of a particular type
e: Width of widest narrow element
E: Width of narrowest wide element
e i : i th edge to similar edge measurement, counting from leading edge of symbol character
K: Smallest absolute difference between a measurement and a reference threshold
k: number of element pairs in a symbol character in a (n, k) symbology
M: Width of element showing greatest deviation from A
m: Number of modules in a symbol character
N: Average achieved wide to narrow ratio
n: number of modules in a symbol character in a (n, k) symbology
R b : Bar reflectance
R D : Dark reflectance
R L : Light reflectance
R s : Space reflectance
R max : Maximum reflectance
R min : Minimum reflectance
RT j : Reference threshold between measurements j and (j+1 ) modules wide
S: Total width of a character
V: Decodability value
V C : Decodability value for a symbol character
X: Nominal narrow element dimension
Z: Average achieved narrow element dimension
5 Measurement methodology
5.1 General requirements
The measurement methodology defined in this standard is designed to maximize the consistency of both reflectivity and bar and space width measurements of bar code symbols on various substrates. This methodology is also intended to correlate with conditions encountered in bar code scanning hardware.
Measurements shall be made with a single light wavelength and a measurement aperture of a diameter defined by the application specification or determined in accordance with 5.2.1 and 5.2.2.
Whenever possible, measurements shall be made on the bar code symbol in its final configuration, i.e. the configuration in which it is intended to be scanned. If this is impossible, refer to annex D for the method to be used for measuring reflectance for non-opaque substrates.
5.2 Reference reflectivity measurements
Equipment for assessing the quality of bar code symbols in accordance with this standard shall comprise a means of measuring and analysing the variations in the diffuse reflectivity of a bar code symbol on its substrate along a number of scan paths which shall traverse the full width of the symbol including both quiet zones. The basis of this methodology is the measurement of diffuse reflectance from the symbol.