Multiple pulse imaging for ANPR / LPR applications

A number of ITS applications, such speed and red light enforcement, require several image captures, taken at different distances, in order to achieve their goals. This can require multiple pulses of light of different intensities to be generated within a very short space of time,this functionality is built into all Gardasoft ITS LED strobes and is known as multi-pulsing^™.

LED lighting systems are particularly suited to such applications, by virtue of the very high pulse rates of which they are capable. LED-based lighting systems can also very rapidly alter the frequency and power of light pulses which, as the figure below demonstrates, is necessary in order to provide the correct light intensities at different distances.

The figure below shows how continually pulsing at a lower intensity and then using a short-duration pulse of higher intensity for image capture can reduce the startling effect on road users.

Figure 5: Constant illumination allied to short, high-intensity pulses for target illumination

The figure above shows the example of a single-point speed enforcement camera, where the issues to address include adequate image quality at multiple positions on the road and what is to be captured in the image (license plate, vehicle colour and model, road markings, surrounding environment and so on). Again, this is dependent on the ability to generate very fast pulse rates at varying frequencies and power outputs, requirements to which LEDs are very well suited.