Perceptics, LLC

Rafael C Gonzalez

Juan Antonio Herrera

A video camera produces an image of a license plate on a vehicle, and a scanning apparatus finds a license plate number in the image. The identification of the license plate number is verified in a confidence check section by checking for the presence of a state logo. Next, a character extractor identifies individual characters of the number by finding and tracing a contour along interior portions of the character edges, and the contour length, character height, and character width are then checked in a validity checking section to determine whether they are within predetermined acceptable ranges. To correct for obscuring objects on the license plate, a character alignment section determines the top line and baseline of the license plate number and disregards portions of the characters that appear to be outside of these limits, and a license plate frame correction section is utilized to extract the characters when a portion thereof is obscured by a license plate frame. Once extracted, the characters are recognized by a structural analysis section and a state recognition section recognizes the state logo. Once the state is identified, a verification section rereads the license plate number utilizing knowledge of the type style used by the identified state.

Apparatus for reading a license plate

An optical system produces an image of a set of characters on a background. A flash light source directs uniform illumination toward the set of characters for a predetermined flash period having an intensity chosen to exceed the intensity of corrupting light from the environment, such as sun light, street lights or car lights. A first polarizer is positioned to polarize the illumination from the flash light source prior to the light impinging on the set of characters, and a second polarizer is positioned to receive light reflected by the set of characters and the background. The second polarizer is cross-polarized with respect to the first polarizer so that it filters out polarized light from the flash light source that is reflected by the set of characters and background. An optical receiver is positioned to receive light from the second polarizer and produces an image of the set of characters and the background. A shutter is used to control the light received by the optical receiver. The shutter is synchronized with the flash light source and the optical receiver to open and close during the flash so that the image produced by the optical receiver is dominantly produced by the de-polarized flash light reflected from the set of characters and background.

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Knoxville, TN, United States of America

Rafael C Gonzalez