What factors affect the accuracy of license plate recognition?

Installation parameters (the most critical)

Equipment selection

• Using the Special License Plate Camera, it has strong light suppression and license plate-specific algorithms, and the effect is far better than that of a general-purpose camera.
• Select a 6~12mm lens with manual zoom, and fine-tune the license plate to the appropriate proportion of the screen on site.
• Large target area sensors (1/1.8″ and above) perform better in low light.

Fill light and backlight

• Fill-in light is necessary at night: Use strobe fill-in light (very bright), Always-on lights can cause driver glare and cause complaints.
• Install the fill light on the same side as the camera to prevent light from shining directly on the lens.
• For strong light from car lights, turn on Highlight Suppression and limit the upper limit of the shutter speed.
• When the entrance faces west, the sunset in the evening will shine directly on the lens, so you need to install a hood or adjust the installation position.

Algorithm and parameters

• Enable license plate duplication and multi-frame comparison to avoid repeated identification of the same vehicle.
• Configure the unlicensed vehicle processing strategy (such as manual confirmation or scan QR code to pass).
• New energy license plates (gradient green, yellow and green) need to confirm that the algorithm version is supported.
• The trailer/tractor must lock the main license plate to avoid recognizing the front of the vehicle.
• Defaced license plates and mud and water are the most difficult situations. It is necessary to check whether the recognition rate meets the business requirements.

Acceptance method

Collect traffic data continuously for 7 days, covering day and night and peak hours, and calculate the recognition rate. Common industry goals: ≥ 99% during the day and ≥ 98% at night.If it is lower than expected, check the installation angle and fill light first. Instead of blindly increasing the algorithm sensitivity.