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Method and apparatus for automatic optical recognition of road signs

  • US 5,633,944 A
  • Filed: 04/19/1995
  • Issued: 05/27/1997
  • Est. Priority Date: 04/19/1994
  • Status: Expired due to Fees
First Claim
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1. A process for automatic recognition of an object comprising the steps of:

  • displaying on a screen an input image containing the image of the object to be recognized as well as images of reference objects;

    causing a first laser beam to pass through this screen and an initial lens in order to focus the first laser beam on a modulator capable of recording an intensity spectrum;

    illuminating the modulator with a second laser beam;

    causing said second laser beam to pass through a second lens as the second laser beam leaves the modulator in order to produce a second spectrum supplied to a detection system; and

    determining whether the image of the object to be recognized is identical to one of the images of reference objects based on the second spectrum;

    wherein the step of determining involves detecting correlation peaks of the various objects contained in the input image, within the focal plane of the second lens, in such a way that the presence of intensity peaks exceeding a predetermined threshold and offset with respect to the optical center of the image indicates that the image of the object to be recognized is identical to one of the images of reference objects; and

    wherein the portion of the beam corresponding respectively to said intensity peaks are polarized differently, and wherein said portions are separated in polarization in order to send them onto different detectors.

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