Omron V440-F User Manual page 212

 Minimum Edge Contrast
Minimum Edge Contrast measurements assume 8-bit 0 – 255 intensity in the captured image cor-
relate directly to 0 – 100% reflectance. Minimum Edge Contrast is an absolute measurement that
ensures each element edge within the symbol achieves a minimum value. Uneven thermal or ink
transfer, or printing on an inconsistent or uneven substrate, can result in areas where the edge of a
bar is difficult to identify. The Minimum Edge Contrast is calculated and graded for each scan and
provided for the overall grade calculation in accordance with the ISO 15416 specification. The
parameter grade and value provided for output is an average value for each measured scan over
the entire symbol.
 Modulation
Modulation is a relative measure of the edge contrast to symbol contrast. A good Modulation
means the printing process is taking full advantage of the contrast available. Good Modulation
becomes important particularly as other areas degrade allowing for relative margin in the reading
process. Modulation is calculated and graded for each scan and provided for the overall grade cal-
culation in accordance with the ISO 15416 specification.The parameter grade and value provided
for output is an average value for each measured scan over the entire symbol.
 Defects
Defects are measurements of anomalies in the printed bars or spaces. These can be from be print-
ing problem or from a variety of other sources such as scratches or problems with the substrate
material. Defects, if large enough, can introduce spaces or bars that don't exist, causing a misread
or failure. Defects are calculated and graded for each scan and provided for the overall grade calcu-
lation in accordance with the ISO 15416 specification. The parameter grade and value provided for
output is an average value for each measured scan over the entire symbol.
 Decodability
Decodability measures the difference in dimension of the decoded symbol characters to the ideal.
The further the characters are from the ideal, the more likely they are to fail to read or produce a
misread. This can be caused by a variety of factors but can often indicate that equipment is not
capable of printing at the resolution required or that the source data for the symbol has been improp-
erly formed or degraded through transformation. Decodability is calculated and graded for each
scan and provided for the overall grade calculation in accordance with the ISO 15416 specification.
The parameter grade and value provided for output is an average value for each measured scan
over the entire symbol.
 Quiet Zone
Quiet Zone is an evaluation of the scan line before and after the start and stop characters. Required
Quiet Zones are dependent on the symbology and evaluated in accordance with symbol specifica-
tions. Note that Quiet Zone is not an individually processed parameter within the ISO 15416 specifi-
cation but is evaluated as part of the ISO graded decode parameter. A failing Quiet Zone scan will
result in a failed Decode scan, which then feeds into the overall grade. The Quiet Zone parameter is
provided as an average scan result where a passing scan receives an A / 4.0 grade and a failing
scan receives an F / 0.0. When the serial output for Quiet Zone is a letter grade, 95% of scans must
pass. When the serial output is a numeric grade, the output shows the passing percentage.
V440-F C-Mount Code Reader User Manual
8 Advanced Settings
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