Abstract: A camera system comprises a CCD imaging device, an infrared illumination source, and a power modulator for amplitude modulating the infrared illumination, e.g., with a 7-kHz tone. A beam splitter is set in front of the CCD imaging device, and a photo-diode array is attached to the beam splitter to detect modulated infrared light returning from the same field of vision as the CCD imaging device Various tone filters, and triggers connected to the tone filters, will cause the CCD imaging device to take a digital picture when the returning modulated infrared light exceeds some threshold and comes from right areas of a picture frame. Such digital pictures will most probably include an image of a vehicle license plate that can be processed, and the results used to extract the registration data from a database.

Abstract: A camera system comprises a CCD imaging device, an infrared illumination source, and a power modulator for amplitude modulating the infrared illumination, e.g., with a 7-kHz tone. A beam splitter is set in front of the CCD imaging device, and a photo-diode array is attached to the beam splitter to detect modulated infrared light returning from the same field of vision as the CCD imaging device Various tone filters, and triggers connected to the tone filters, will cause the CCD imaging device to take a digital picture when the returning modulated infrared light exceeds some threshold and comes from right areas of a picture frame. Such digital pictures will most probably include an image of a vehicle license plate that can be processed, and the results used to extract the registration data from a database.