ANPR
© Nedap AVI, P.O. Box 103, NL-7140 AC GROENLO Page 13 of 27
Char Size Pixel
These parameters represent the size of the plate characters the OCR video camera is to recognize. The maximum
and minimum character sizes should be empirically set upon installation, in order to check whether the OCR
recognizes the number plates.
Min Width: The minimum character width in pixels.
Max Width: The maximum character width in pixels.
Min Height: The minimum character height in pixels.
Max Height: The maximum character height in pixels.
Procedure for adjusting the character size settings:
1. In the Camera OCR page, take a shot of the number plate under the actual conditions later used in the
ANPR system.
2. Use the Result Position setting in order to activate the OCR results image overlay feature.
3. Now, when the plate reading occurs, on the image is displayed not only the number plate but also the
character size in pixels.
4. Enter these size values in the Plate Reader page, using the exact minimum and maximum values
displayed on the screen during the live capture from the most distant vehicle position (min. size) and
the nearest vehicle position (max. size).
5. If number plate reading is not reached, try and set a higher character maximum size, until a valid
reading is reached.
6. In the Result web page, it is possible to read the character size of last detected vehicle. This is useful
when checking the validity of the character size setup during system operation.
Note: Character size adjustment is important and can significantly improve the overall system performance.
Plate Format
Max Jolly Chars: This feature allows setting the maximum number of plate characters the ANPR reader
is allowed not to recognize within the number plate. If set to 0 (zero), the reading is
valid only if the ANPR recognizes every character of the number plate. If set 1 or 2
(maximum value), the ANPR will consider the reading valid while the unrecognized
characters are replaced by a Jolly character – represented by the # symbol. Number
plate readings with jolly characters generate an OCR_READ event.
Plate With Separator: If enabled (YES) then an underscore character ('_') is inserted between the number
plate character groups. Only for German plates (DEU).
Plate Rotation %: This allows setting the plate rotation. This may improve the ANPR performance when
installed under an angle. The value is set in the range from 0 to 100%. When set to -1
the ANPR will automatically learn the plate rotation from the first 20 number plates.
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