Positional detector device for a vehicular license plate

Abstract

In a positional detector device for a license plate of a motor vehicle, a camera is provided to photograph a front and rear portion of a motor vehicle so as to produce an image signal. An A/D converter converts the image signal into a digital image. A positional detector detects a position of a lisence plate of a motor vehicle based on the digital image. A cut-off treatment device cuts off a specified region from an original image photographed by the camera while scanning the original image when the motor vehicle approaches the camera member within a predetermined distance. An edge refining treatment device emphasizes a contour of a pattern represented by the specified region cut off from the original image. A contraction treatment device contracts an image size of the specified region which was treated with the edge refining treatment device. A calculation treatment device feeds the contracted pattern to a learned neural network so as to calculate an output value for a positional detection neural network. A coordinate transformation device transforms the output value of the positional detection neural network to such a scale as to meet the original image. An addition treatment device adds data at specified points which were multiplied by Gaussian window so as to obtain a projective addition value after carrying out the coordinate transformation. A distinction treatment device recognizes a position of the license plate based on a maximum value on which the projective addition value falls.