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.
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.
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ENGLISH
Symbol contrast
≥
70 %
≥
55 %
≥
40 %
≥
20 %
< 20 %
Rating
A
B
C
D
F
