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Image processing
3.2 Code verification
SIMATIC MV500
64
Operating Instructions, 03/2021, C79000-G8976-C494-05
• Symbol contrast:
Difference between the maximum and minimum reflectance.
• Decodability:
The proportion of the available surrounding space (between the ideal dimension of an
element or a combination of elements and the relevant reference threshold value) that is
not used by the element or the combination of elements. The ratio is calculated for the
element or the combination of elements that deviates most from the ideal dimension.
• Defects:
Irregularities in elements and quiet zones measured based on the non-uniformity of the
reflectance of the elements.
• Modulation:
Ratio of the minimum edge contrast to the symbol contrast.
• Start quiet zone:
Area outside the start code word with a length of 10 modules.
• Stop quiet zone:
Area outside the stop code word with a length of 10 modules.
Table 3- 7 Assignment of the numeric grade of ISO/IEC 15416 to the quality grades
Quality features
(abbreviation)
Quality grades Comment
4 3 2 1 0
Scan reflectance profile Lowest single grade per scan line --
Edge determination pass -- -- -- fail --
Reference decoding pass -- -- -- fail --
Minimum edge contrast (MEC) ≥ 0.15 -- -- -- < 0.15 --
Minimum reflectance (RMI) ≤ 0.5R
max
-- -- -- > 0.5R
max
R
max
is the maximum re-
flectance.
Symbol contrast (SC_) ≥ 0.70 ≥ 0.55 ≥ 0.40 ≥ 0.20 < 0.20 --
Decodability (DEC) ≥ 0.62 ≥ 0.50 ≥ 0.38 ≥ 0.25 < 0.25 --
Defects (DEF) ≤ 0.15 ≤ 0.20 ≤ 0.25 ≤ 0.30 > 0.30 --
Modulation (MOD) ≥ 0.70 ≥ 0.60 ≥ 0.50 ≥ 0.40 < 0.40 --
Quiet zone (QZ_) ≥ 10
modules
-- -- -- < 10
modules
--
3.2.7 DotCode verification
The quality evaluation of DotCodes is based on ISO/IEC 16022 but has been adapted to the
specific properties of this code type. As a result of the adaptation, "Axial non-uniformity" has
been replaced with "Grid non-uniformity".