Panasonic IMAGECHECKER PV230 Manual page 41

3.
Select a filter from "No", "2x2
Erosion->Dilation", "3x3 Erosion->Dilation",
"4x4 Erosion->Dilation" or "5x5
Erosion->Dilation".
Default: "No"
"Filter" is not available when "Recognition rate
method" is "Correlation Value". In this exercise,
select a filter condition for subtraction results.
Filter (Optical Character Recognition)
Minute pixels of the result of subtraction can be deleted by using the [Erosion->Dilation] filter. The larger
value is set to the filter, the higher effect is achieved on the deletion.
4.
Enter a threshold value of the
gray range for the subtraction
process in "Subtraction
Threshold".]
Default: "128"
"Subtraction Threshold" is not
available when "Recognition rate
method" is "Correlation Value".
• The contour of characters can be extracted more easily by setting a smaller subtraction threshold. Set a
value that is large enough to detect missing characters and dirt.
• When using a featureless image (i.e. no variation in luminance, and featureless shape), note that the
recognition rate is 100% due to the algorithmic property of recognition rate even if there is a missing
character.
For example, if a character "-" (hyphen) created on a PC is read as an image file using "Read Image" of
PV230, the recognition rate is output as 100% even if the character "-" is missing.
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