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Smart Camera / Vision-Sensor / 1D-/2D-Code-Scanner / OCR Reader
Orientation
Tolerance
Orientation tolerance. Please refer to the explanation of ’Orientation’ parameter for
further information. As explained there, relevant orientation values are only in the range
of [-90.0 . . . 90.0], which means that with ’Orientation Tolerance’ = 90 the whole range
is spanned. Therefore valid values for ’Orientation Tolerance’ are only in the range of
[0.0 . . . 90.0]. The default value 90.0 means that no restriction on the bar code candi-
dates is performed. Typical values: [0.0 . . . 90.0] Default: 90.0
Start Stop
Tolerance
Enforces a tolerant (’high’) or strict (’low’) searching criteria, while inspecting a scan-
line for a start or stop pattern, respectively. A more tolerant criteria will generally in-
crease the detection chances of a bar code, provided that a clear symbol is imaged
in the processed image. On the other side, it might result in false detections in noisy
images or images containing symbols from other symbologies. Less tolerant criteria
increase the robustness against false detections, but might reduce the general detec-
tion rate. Currently, there are two distinct criteria implemented only for Code 128.
List of values: [’high’, ’low’] Default: ’high’
Threshold
’Threshold’ defines a threshold, which is a relative value with respect to the dynamic
range of the scanline pixels. The barspace-sequence of a bar code is determined
with a scanline measuring the position of the edges. Finding these edges requires
the mentioned threshold. In the case of disturbances in the bar code region or a high
noise level, the value of ’Threshold’ should be increased. Typical values: [0.05 . . . 0.2]
Default: 0.05
Threshold
Absolute
If a scanline is laid in an image region with no or just very small gray value dynamic
range (e.g., in a white region with all gray values near 255), the edge detection thresh-
old based on ’Threshold Absolute’ would be computed unreasonably small. This leads
typically to the detection of a big amount of false edges. ’Threshold Absolute’ is used
to prevent such misdetections. If the threshold value based on ’Threshold’ gets smaller
than the value of ’Threshold Absolute’, the latter is used as threshold instead. By de-
fault, ’Threshold Absolute’ is set to 5.0. A greater value might be more appropriate
for images with high noise levels. On the other hand, in noise-free images with very
weak contrast, this parameter might disturb the detection of real edges, so it might be
necessary to reduce it or even completely disable it by setting it to 0.0. Typical values:
[0.0 . . . 10.0] Default: 5.0
Max Different
Orientation
A potential bar code region contains bars, and hence edges, with a similar orientation.
The value “Max Different Orientation” denotes the maximum difference in this orienta-
tion between adjacent pixels and is specified in degrees. If a bar code is of bad quality
with jagged edges, the parameter “Max Different Orientation” should be set to higher
values. If the bar code is of good quality “Max Different Orientation” can be set to lower
values, thus reducing the number of potential but false bar code candidates. Typical
values: [2 . . . 20] Default: 10
Check
Character
For bar codes with a facultative check character, this parameter determines whether
the check character is taken into account or not. If the bar code has a check character,
’Check Character’ should be set to ’present’ and thus the check character is tested.
In that case, a bar code result is returned only if the check sum is correct. For ’Check
Character’ set to ’absent’ no check sum is computed and bar code results are re-
turned as long as they were successfully decoded. Bar codes with a facultative check
character are, e.g. Code 39, Codabar, 2/5 Industrial and 2/5 Interleaved. List of values:
[’absent’, ’present’] Default: ’absent’
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