Siemens SIMATIC MV420, Operating Instructions Manual

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Image processing
4.3 Optical character recognition with "Text-Genius" and "Text-Genius Plus" (SIMATIC MV440 only)
SIMATIC MV420 / SIMATIC MV440
84
Operating Instructions, 04/2013, A5E02371045-06
4.3.6 Quality characteristics in optical character recognition
Fast feedback about the reliability of the character recognition
To obtain fast feedback about the reliability of the character recognition: In much the same
way as code verification, during optical character recognition, quality characteristics are
calculated and output on the user interface or via the interfaces.
Quality characteristic Value output
Poorest character quality The value output is the poorest (lowest) probability value of all the
characters found.
Since plain text cannot be uniquely identified, a probability is
calculated for a character that is found. This can be interpreted as a
match between the printed a theoretical, "ideal" character.
Highest confusion risk The value output is the poorest (lowest) probability difference of all
the characters found.
For each identified character position, up to seven character
hypotheses each with their own probability are calculated. The
hypothesis with the highest probability is selected as the read result
for the character position. The confusion risk is the difference in
probability between the two hypotheses with the highest evaluation.
Minimum character height Height in pixels of the smallest character found measured
perpendicular to the reading direction.
Maximum character height Height in pixels of the highest character found measured
perpendicular to the reading direction.
Average character quality Average probability of all characters found
Average confusion risk Average probability difference for all characters found
Assignment of the numeric evaluation of OCR to the quality levels
Grade 4 3 2 1 0
Poorest character quality (OCQ) ≥ 208 ≥ 156 ≥ 104 ≥ 52 < 52
Highest confusion risk (OCC) ≥ 208 ≥ 156 ≥ 104 ≥ 52 < 52
Minimum character height (OCL) > 26
and
≤ 30
> 30 and
< 40
≥ 20 and
< 25
or
≥ 40 and
< 45
≥ 45 and
< 50
< 20
or
≥ 50
Maximum character height (OCH) > 26
and
≤ 30
> 30 and
< 40
≥ 20 and
< 25
or
≥ 40 and
< 45
≥ 45 and
< 50
< 20
or
> 50
Average character quality (OAQ) ≥ 208 ≥ 156 ≥ 104 ≥ 52 < 52
Average confusion risk (OAC) ≥ 208 ≥ 156 ≥ 104 ≥ 52 < 52