A License Plate Recognition and Speed Detection System - Index of

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according to the time of day or weather. Therefore, only the uniform, constant light provided by an LPR light source should be allowed to enter the camera Another desired LPR light source characteristic is to output light with high intensity. This is due to several factors. For one, the license plate will be distant from the camera. More distant objects reflect less light back to the camera. Two, the camera will use a fast exposure setting in order to reduce image blur caused by the motion of the high speed vehicle. Three, the telephoto lens used by the camera to magnify the image as well as the filter placed in front of the camera will limit the amount of light received. And four, most CCD chips are not as sensitive to light in the near infrared range requiring more light be received for the same image contrast. All of these factors will cause the license plate image to appear dark and lessen its level of detail. However, an LPR light source with very high intensity can offset these negative effects. The more light that is emitted by a light source, the more light will be received by the camera. With more light, the camera image will contain more detail, making image processing routines more accurate. Another desirable LPR characteristic is to project a beam of light that illuminates the entire width of the street lane. This will ensure that as long as a vehicle stays within its lane, its license plate will be illuminated when it passes. A summary of desirable LPR light source characteristics is given in the table below. When a light source contains these characteristics, the intended license plate will be properly illuminated. Table 1 LPR Light Source Characteristics Characteristic Desired Value Physical Location As close as possible to camera aperture. Wavelength of light Near infrared 12
Uniform and Constant To be as uniform and constant as Intensity possible. Power of intensity To provide enough lighting so that image detail meets image processing requirements. Projection Beam Angle To cover entire width of street lane. III.B. LPR Camera The second component of a license plate recognition system is the video camera. The video camera captures images of passing vehicles and transfers those images to the computer. An industrial or computer vision grade video camera provides the characteristics required by LPR systems. A good example is the LXR CX800 (specifications are given in Appendix B). A video camera for license plate recognition has three components; a long pass filter, a telephoto lens, and a CCD chip. A description of these components and their characteristics is provided in the following paragraphs. Digital Signal Output Video Camera Components CCD Chip in Camera Telephoto Lens As depicted in figure above, light first passes through a long pass. This filter blocks light in the short wavelength region (less than 720nm) and allows light with longer wavelengths (the infrared region) to pass through. A graph of this effect is given below. 13 Long Pass Filter Fig. 7 Video Camera System Light Input License Plate Image
Page 1 and 2: A License Plate Recognition and Spe
Page 3 and 4: I. Abstract Since the 1980’s law
Page 5 and 6: II. Introduction The purpose of thi
Page 7 and 8: III. License Plate Recognition Conc
Page 9 and 10: III.A. LPR Light Source There are s
Page 11: eflective paint effect greatly incr
Page 15 and 16: “Horizontal angle must not exceed
Page 17 and 18: The video camera has another compon
Page 19 and 20: width is only 5/16” will be 3 pix
Page 21 and 22: signal, such as NTSC, a capture car
Page 23 and 24: choose a trigger that will require
Page 25 and 26: We briefly considered laser rangefi
Page 27 and 28: Fig. 17 Doppler Effect (Ref. 14) Th
Page 29 and 30: In this project, we will be using t
Page 31 and 32: V. Our System Design and Implementa
Page 33 and 34: LPR/SD System Process Flow Retrieve
Page 35 and 36: Fig. 25 Image of our LPR/SD system
Page 37 and 38: Our video camera served two functio
Page 39 and 40: V.B.2. Radar Gun The Ramsey Kit Ram
Page 41 and 42: Fig. 31 Assembled Oscillator The mi
Page 43 and 44: up to 100MHz. Once the signal has b
Page 45 and 46: I will discuss the pathway the inpu
Page 47 and 48: Fig. 35 Comparator Operation The si
Page 49 and 50: V.B.3. Serial Interface Circuit Boa
Page 51 and 52: we set pins 8 to 15 as input pins a
Page 53 and 54: Application Main Window Fig. 37 LPR
Page 55 and 56: Fig. 40 LPR.exe application windows
Page 57 and 58: Serial library was written by Ramon
Page 59 and 60: W1, B2, B3, B4, W5, B6, B7, B8, B9,
Page 61 and 62: characters were first extracted. Th
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Plate Number - 791GPB Test Results
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VI. Additional Applications The lic
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needed to communicate with the traf
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Local Network Fig. 50 LPR applicati
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VII. State of the Art Commercial Sy
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100 MHz wide or 200 MHz wide. Since
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As with any new technology affectin
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law, a warrant-less crime must be c
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experience high traffic volumes or
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quite a fun experience to build the
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15) Radar Setup: http://mpdc.dc.gov
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Appendix A: Our LPR/SD System Compo
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Appendix B: Commercial Components 8
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MDL LaserAce® IM OEM Laser Modules
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UF500 Infrared Illuminator 91
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HI-TECH Solutions SeeCar Software R
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Appendix C: Camera Setup Calculatio
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