System for simultaneously imaging vehicles and their license plates

A vehicle and license plate imaging system, comprising:

• a video camera for providing an image of a vehicle and a reflective-paint license plate;
• a first polarizing filter mounted in front of the video camera and having a first polarizing orientation;
• a white-light light-emitting-diode (LED) array for providing a non-polarized illumination of said vehicle and reflective-paint license plate for the video camera;
• a flash lamp for providing a flash illumination of said vehicle and reflective-paint license plate for the video camera;
• a visual-spectrum cutout filter placed between the flash lamp and said vehicle and providing for a blockage of human-visible light spectra from the flash lamp that would otherwise reach said vehicle, and providing for a combination of a first light with wavelengths less than 400 nanometers and a second light with wavelengths more than 700 nanometers at the fringes of the visible spectrum to contrast a variety of color combinations used in said license plate;
• and
• a second polarizing filter placed between the flash lamp and said vehicle, and having a second polarizing orientation that is orthogonal to said first polarizing orientation;
• wherein, any light from the flash lamp with said second polarizing orientation that is returned from said vehicle and said retro-reflective-paint license plate is substantially blocked by the first polarizing filter, and light with no particular polarization that is returned from said vehicle and said retro-reflective-paint license plate can substantially pass by the first polarizing filter;
• and
• wherein, the white-light LED array is able to provide sufficient illumination for the camera if said license plate is a retro-reflective type.

A method of simultaneously imaging a vehicle and its license plate when such license plate may or may not be painted with reflective paints and can comprise any number of contrasting colors, the method comprising the steps of:

• flood-illuminating a vehicle and its license plate with a non-polarized light sufficient to return a usable visible image from a retro-reflective-paint license plate;
• flash-illuminating said vehicle and its license plate with a polarized light sufficient to return a usable visible image from said vehicle and any non-retro-reflective-painted license plate, and providing for a combination of a first light with wavelengths less than 400 nanometers and a second light with wavelengths more than 700 nanometers at the fringes of the visible spectrum to contrast a variety of color combinations used in said license plate;
• filtering out any of said polarized light returned from said vehicle and its license plate before it reaches a camera;
• imaging said vehicle and its license plate with a camera;
• and
• wherein, the non-polarized light is able to provide sufficient illumination for the camera if said license plate is a retro-reflective type.