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General adjustment:
The lens has to be setup in order to have the width of the
licence plate equal to 1/3 the width of the image.
Adjustment of the lens:
1/3
14px by character
-
-
200px for a standard 50cm licence plate
Adjustment of horizontality
The software can automatically correct oblique plates. The
aim of this functionality is to correct horizontality-related
flaws due to the terrain (sharp angles, bumpy road, plates
badly attached, and camera subject to vibrations...).
Nevertheless, if the plate is too oblique, the software will
have difficulties in finding, adjusting and reading the plate.
Therefore, the camera box must be fixed so that the plate
is as horizontal as possible in the image. The easiest way
~14px
1/3
1/3
to make sure that the image is horizontal is to verify that
plates are well parallel to the image's upper or lower side.
Bad horizontality:
Good horizontality:
Adjustment of the focal length
and the sharpness
The adjustment of the focal length must be carried out
according to the same rules as the one indicated in the
chapter "choosing the lenses".
The image must be sharp when the plate's width is
between a fourth and a third of the width of the image.
In order to have a good sharpness setting, it is
recommender to open (O) the iris, while keeping a visible
image, at approximately 75-80% of the maximum opened
setting. The Software will automatically adapt the shutter
speed at a very high value in order to have a good contrast.
For indoor applications, set the shutter speed value
manually, between 1/ 500s and 1/4000s, depending on the
distance of the car.
Adjustment of framing
The Sony camera is always looking for a licence plate
everywhere in the image.
Nevertheless, the entire plate should be present in the
image as long as possible. A bad framing can lead to a too
short vision of the plate by the software or to a partial view
of the plate. In both cases, performances will be
undermined.
The best framing is the one that makes the plates move
diagonally across the image. Thus, the entire plate will be
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