Image processing
4.2 Code verification
SIMATIC MV420 / SIMATIC MV440
50 Operating Instructions, 04/2013, A5E02371045-06
4.2.4 Data matrix verification
4.2.4.1 Siemens DPM
In Siemens DPM verification, the user can select the test parameters to be used and
configure the levels "Good", "Fair" and "Poor" for every test parameter individually.
The range of options for verification is ideal for process control in data matrix applications in
which no public standard needs to be adhered to.
Note
"Symbol contrast" and "Cell size"
The test parameters "Symbol contrast" and "Cell size" are not active in the default setting
because these parameters can only make limited statements regarding direct part marks.
They can be activated in the adjustment support.
Quality parameters
● Cell size:
The overall width divided by the number of columns or the overall height divided by the
number rows. The value output is the cell size in mils (milli-inches). The assignment to
the quality level is based on the number of pixels: See "Assignment of the numeric grade
of Siemens DPM to the quality levels".
● Center offset:
Measurement of the offset of the cell center to the center of the ideal grid starting at the
four corners of the codes.
● Size offset:
Measurement of the difference in cell sizes compared with each other.
● Cell modulation:
Measurement of the uniformity of the reflection values of the dark cells compared with the
light cells.
● Border match:
Percentage of border cells that match the pattern formed by the four borders of the data
matrix.
● Symbol contrast:
Difference between the average reflectance of the lightest pixels and the darkest pixels.
● Axial non-uniformity:
Difference between the height and width relative to the rows and columns.
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