Positional detector device for a vehicular license plate

• US 6,281,928 B1
• Filed: 05/13/1998
• Issued: 08/28/2001
• Est. Priority Date: 05/13/1998
• Status: Expired due to Fees

• Current Assignee: UME Tech Yugen Kaisha
• Original Assignee: Chuo Hatsujo Kabushiki Kaisha
• Inventors: Umezaki, Taizo, Kanade, Takeo, Matsumoto, Noriyuki
• Primary Examiner(s): Kelley, Chris
• Assistant Examiner(s): An, Shawn S.
• Application Number:
  US09/076,791
• Time in Patent Office: 1,203 Days
• Field of Search: 348/148, 348/149, 382/105, 382/278, 382/284, 382/282, 382/299, 382/300, 340/933, 340/937, 340/928, 340/905, 340/901
• US Class Current: 348/148
• CPC Class Codes: G06T 2207/10016 Video; Image sequence
• CPC Class Codes: G06T 2207/30252 Vehicle exterior; Vicinity of vehicle
• CPC Class Codes: G06T 7/11 Region-based segmentation
• CPC Class Codes: G06T 7/73 using feature-based methods

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.

Claims

1. A positional detector device for a license plate of a motor vehicle comprising:

a camera member which photographs a front and rear portion of a motor vehicle so as to produce an image signal;

an A/D converter which converts the image signal into a digital image;

a positional detector member which detects a position of a lisence plate of a motor vehicle based on the digital image;

a cut-off treatment member which cuts off a specified region from an original image photographed by the camera member while scanning the original image when the motor vehicle approaches the camera member within a predetermined distance;

an edge refining treatment member which emphasizes a contour of a pattern represented by the specified region cut off from the original image;

a contraction treatment member which contracts an image size of the specified region which was treated with the edge refining treatment member;

a calculation treatment member which 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 member which transforms the output value of the positional detection neural network to such a scale as to meet the original image;

an addition treatment member which 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; and

a distinction treatment member which recognizes a position of the license plate based on a maximum value on which the projective addition value falls.

3. A positional detector device for a license plate of a motor vehicle as recited in claim 1 or 2, wherein learning of the neural network is based on a back propagation method which employs learning date and teaching data, and a unit threshold function is based on sigmoid function.

4. A positional detector device for a license plate of a motor vehicle as recited in claim 1 or 2, wherein the detector device is used to recognize a number of the license plate when the motor vehicle passes through a highway toll gate without stopping there.

2. A positional detector device for a license plate of a motor vehicle comprising:

a camera member which photographs a rear portion of a motor vehicle so as to produce an image signal when the motor vehicle approaches the camera member within a predetermined distance;

an A/D converter which converts the image signal into a first sized original image;

a positional detector member which detects a position of a lisence plate of a motor vehicle based on the original image;

a cut-off treatment member which cuts off a second sized region from the first sized original image photographed by the camera member while scanning the first sized original image;

an edge refining treatment member which emphasizes a contour of a pattern represented by the second sized region cut off from the first sized original image;

a contraction treatment member which contracts the second sized region into a third sized image after treated with the edge refining treatment member;

a calculation treatment member which feeds the contracted pattern of the third sized image to a learned neural network so as to calculate an output value for a positional detection neural network as a fourth sized image value;

a coordinate transformation member which projects the output value of the positional detection neural network to a positional distinction pattern, a size of which is the same as that of the first sized region, and transforming the fourth sized image value into the second sized region;

an addition treatment member which adds data at specified points which were multiplied by Gaussian window to a positional distinction pattern of the license plate so as to obtain a projective addition value after carrying out the coordinate transformation; and

a distinction treatment member which recognizes a position of the license plate based on a maximum value on which the projective addition value falls.