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Navigation: Gatekeeper-X models > Optimise ANPR

Setting zoom and focus

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To get optimal recognition adjust  zoom and focus in a way that the license plate is sharp and its width is between 100 and 300 pixels.

Both the settings- and viewpanel of the GatekeeperAxon are used to configure the settings.

In CortexView open both panels.

 

 

Step 1: Automatic zoom and focus

CC_GatekeeperAxon_viewpanel_focus

 

GatekeeperAxon viewpanel:
Drag a rectangle around the license plate, while holding left mouse button. It will automatically adjust zoom and focus levels to obtain a sharp image ready for recognition. Tweaking zoom and focus level can be done manually (see step 3)

 

 

 

 

Step 2: Determine the proper zoom and focus levels: ANPR inspection tool

 

 

CC_GatekeeperAxon_viewpanel

 

 

 

To visualize ANPR, right click on the image of the GatekeeperAxon viewpanel and choose 'Anpr'. The recognition overlay should now be visible.

If the overlay is not visible the license plate will be either too big or too small and no license plate is recognized. Adjust zoom levels until the overlay is visible (see step 3).

 

Explaining the numbers

1.License plate size
The top number highlighted in green at the top right corner of the license plate represents the width of the license plate. It should be anywhere between 100-300 for optimum performance.  The bottom number representing the height of the plate should be higher than 20. If the numbers are out of bounds they will turn red and need adjusting,  try to optimize by changing the zoom level.

2.The tilting angle of the license plate
The number left of the license plate shows the angle of the license plate in degrees, this should be under 10, again this will turn red if it needs adjusting.

3.Zoom/focus level
In this example the license plate is 224px wide, the average character height is 50 pixels. The number in red shows that the current zoom/focus level is 121. Zoom/focus can be better here. It can go to 345, the maximum zoom/focus it has measured so far in this image.

4.Recognized license plate
The characters above the license plate are the recognized characters. It is not the end result. The end result is display in the center on top of the window.
 

 

 

The inspection tool schematic

 

 

CC_ANPR_optimise-tool

 

 

 

 

Step 3: The GatekeerAxon settingspanel (expert tab): to manually set zoom and focus

 

CC_GatekeeperAxon_expert_mode

 

 

Setting

Min value

Max value

Description

Zoom

0

1000

To zoom in or out.

When moving zoom focus will adjust automatically.

Focus

0

1000

To adjust the focus

Led

0

255

To adjust the strength of the led's

Iris

0

1000

To open or close the iris manually.

Iris set point

0

255

The iris set point is the value of the average brightness of the image. The iris will continually adapt to try to achieve this setting.

If multiple sequences are active in the IDS settings, choose what sequence you are setting the iris for, in the ‘Sequence id’ setting. In general, you will set the iris for the darkest sequence, keeping the iris relatively closed. All subsequent sequences will be lighter.

By default, the iris set point is set to 80, but in some cases, it may be necessary to adjust this value, for instance in extreme dark or light conditions.

Auto iris

Set iris to automatic adjustment to current lighting conditions. It will make the iris adjust to the iris set point.

Source

The source of the video stream.

Sequence

1

2

Set the sequence the auto iris uses to adjust to. See 'iris set point' (above) for more details.

Filter

off

on

To manually set the IR cut filter on or off. The filter stops infrared light reaching the sensor.
Important: Leave unchecked for GK410 and GK1250. The sensors of these models are infrared sensitive. Recognition is done in this spectrum.

The daylight filter only transmits infrared light.