TrueANPR^TM Technology

Plate Recognition in any Lighting

Many cameras are available today which claim to be suitable for ANPR but which will fail in many common lighting conditions. This is because they do not include any optical filtering or pulsed IR illumination. Here is a comparison of our TrueANPR cameras with a popular third party ANPR camera in some very common lighting scenarios.

This is a common problem with ANPR cameras which have no optical filtering. The low sun is reflecting back very strongly from the plate but there is part shade from trees, foliage, a palisade fence or perhaps a gatehouse building. Even though the Wide Dynamic Range feature is enabled, the camera is unable to cope with the ultra-high contrast range caused by sunlight on the retro-reflective plate.

This camera will suffer many mis-reads whilst these conditions persist, with often only part of the plate being recorded. If this camera is controlling a barrier, many authorised users will not gain entry and confidence in the system may be lost.
With the TrueANPR camera, the combined optical filtering and pulsed infrared illumination work together to eliminate the reflected sunshine and then illuminate the plate evenly.

TrueANPR cameras are always monochrome, even during the day, in order to combat sunlight issues. Where a colour image of the vehicle is required, just add one of our SnapShot plug-in colour overview cameras.

Part Shade

Basic ANPR

TrueANPR
Here you can see that the third party colour ANPR camera, despite having a Wide Dynamic Range feature, is struggling with the strong morning backlighting. Whilst it is possible to manually adjust the camera brightness in order to cope with this scenario, the camera will then definitely fail at the end of the day when the sun is behind the camera and the reflective plate becomes over-exposed (see next comparison).

This camera will fail to capture any plates for perhaps an hour or two on every sunny morning for typically 2-3 months of the year. If this camera is being used to automatically open a barrier, vehicles will not be able to gain access during these periods and the barrier will have to be left open.
Because the TrueANPR camera includes an optical filter to remove much of the daylight in the scene, this camera will always expose the plate correctly. Despite this difficult lighting situation, the pulsed infrared LED array illuminates the plate perfectly.

Our SnapShot cameras have a combined viewing range of 3-40 metres and all of them feature continuously adjustable LED infrared power to ensure perfect plate illumination at any distance.

Strong Back Lighting

Basic ANPR

TrueANPR
Now with the sun directly behind the camera, the reflective number plate is over-exposed and the recognition will fail. Again, it is possible to manually adjust the camera brightness for this scenario, but there is no single camera setting that will allow a colour camera to cope with strong front and back lighting of a reflective plate, even when the Wide Dynamic Range setting is employed.

This camera will fail to operate for long periods on each sunny evening for several months each year.
The optical filtering used by the TrueANPR camera significantly reduces the reflected sunlight and ensures the plate is correctly exposed.

Strong Front Lighting

Basic ANPR

TrueANPR
Fast Movement
Colour ANPR cameras obviously rely on ambient light during daylight hours and, to ensure the camera will still work on a murky winters day, this tends to limit the maximum practical shutter speed to around 1/500^thsec.

Whilst this will be acceptable for some installations, where there is significant movement of the plate within the scene, the captured plate image will show some degree of motion blur leading to recognition errors. Note that motion blur does occur with very slow-speed vehicles when the camera is viewing the vehicle at an acute angle, so this problem can exhibit itself even with access control applications.

All the SnapShot cameras have a shutter speed of 1/10,000^thsec in order to freeze the plate for a pin-sharp image. This fast shutter speed is made possible by the pulsed illumination and is a common feature of TrueANPR cameras.

Basic ANPR

TrueANPR

All our cameras include TrueANPR^TM technology to ensure that license plates are correctly illuminated under all ambient lighting conditions. They achieve this by taking full control of the plate illumination to ensure that other lighting sources, such as the sun or vehicle headlights, cannot adversely affect the image exposure.

Part Shade

Part Shade Basic Part Shade True

Basic ANPR cameras struggle to cope with high contrast scenes and often fail when a plate is in part-shade, but the pulsed infrared and optical filtering of the TrueANPR camera always ensure success.

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Strong Back Lighting

Strong Back Lighting True

Strong backlighting leaves many basic ANPR cameras struggling to produce an acceptable image but the TrueANPR camera’s infrared lighting ensures perfect results.

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Strong Front Lighting

License plates are very reflective causing many basic ANPR cameras to over-expose, but the TrueANPR camera’s optical filtering ensures the reflected sunlight is effectively controlled.

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Fast Movement

In dull or dark condiitons, many basic ANPR cameras have to use very slow shutter speeds which result in blurred images. All SNAP ANPR cameras have a constant shutter speed of 1/10,000^th second to ensure pin-sharp images at any vehicle speed.

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Our products are available to installers, distributors and system integrators
If you are looking for an ANPR system for your own use, please call to discuss your requirements and we can advise of a suitable reseller

0333 6000 063
info@videofit.co.uk

Videofit Limited
Cheltenham UK

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TrueANPR™

TrueANPRTM Technology

Plate Recognition in any Lighting

Part Shade

Strong Back Lighting

Strong Front Lighting

Fast Movement

TrueANPR^TM Technology