Data Matrix Quality Features - IFM Electronic efector 190 Data Matrix Notice Pour Utilisateurs

Data Matrix quality features

The ISO/IEC 16022 standard defines five features to assess the quality of a Data Matrix
code. These features are analysed independently and given five ratings A, B, C, D, F
(A for very good, F for very bad).
The individual feature with the worst rating determines the overall quality of the code.
Feature 1: Decoding
Rating A, if the code can be decoded, otherwise rating F.
Feature 2: Symbol contrast
The symbol contrast is calculated from the ratio of the mean value of the darkest 10%
of the image pixels and the mean values of the lightest 10% of the image pixels. It is
rated according to the following table.
Symbol contrast
Rating
Info
The symbol contrast is an important value. Please note that the visual impression does not nec-
essarily correspond to the calculated value. For scenes with a low contrast (symbol contrast
below 20%) lighting should be optimised.
Feature 3: Print growth
This feature describes the standardised area covered by light and dark modules.
Feature 4: Axial distortion
The axial distortion is a measure for the ratio of the module size in horizontal and ver-
tical direction. For evaluation the modules of the alternating grid are used.
Info
To eliminate interfering reflections the codes are often looked at by a reader located at an incli-
nation angle to the image plane (the code then appears to be trapezoidal). This will often result
in the F rating for the axial distortion and thus an overall evaluation of only F. Nevertheless the
code can be reliably read.
Feature 5: Unused error corrections
The number of unused error corrections is a measure for the degree of distortion of
the code and what part of the existing error correction mechanisms was necessary to
nevertheless decode the code successfully.
≥ 70 % ≥ 55 %
A B
≥ 40 % ≥ 20 %
C D
< 20 %
F
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