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Fingerprint processing system capable of detecting a core of a fingerprint image by statistically processing parameters

  • US 5,040,224 A
  • Filed: 04/24/1989
  • Issued: 08/13/1991
  • Est. Priority Date: 04/23/1988
  • Status: Expired due to Term
First Claim
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1. A fingerprint processing system for use in detecting a position of a core in a fingerprint image which has a plurality of ridges, each having a curvature and a direction, said ridges being quantized into picture elements together with their background, said system comprising a direction and curvature memory having a plurality of memory addresses in correspondence to said picture elements, respectively, for memorizing curvature signals and direction signals and a processing unit coupled to said curvature and direction memory for successively processing said curvature signals and said direction signals to detect said position, said curvature and said direction signals being extracted from said picture elements to represent the curvatures and the directions, respectively, the improvement wherein:

  • said processing unit comprises;

    statistically processing means coupled to said curvature and direction memory for successively and statistically processing said curvature and said direction signals at said picture elements to calculate parameters defined by existence probabilities of said position which are calculated in correspondence to combinations of said directions and said curvatures of the ridges; and

    position determining means connected to said statistically processing means for determining said position from the parameters;

    said statistically processing means comprising;

    a probability thesaurus having a plurality of thesaurus addresses corresponding to combinations of said curvatures and said directions of the ridges for memorizing, in each of said thesaurus addresses, a relative existence probability set of said position which is calculated in relation to a normalized reference picture element and a plurality of adjacent normalized picture elements adjacent to said normalized reference picture element to produce said relative existence probability set, said relative existence probability set being produced one at a time in response to said combinations;

    accessing means coupled to said curvature and direction memory and said probability thesaurus and successively supplied with the curvature and the direction signals memorized at each of said memory addresses for accessing said probability thesaurus to extract the relative existence probability set from the thesaurus address corresponding to said combination of the curvature and the direction signals and to produce the relative existence probability set together with a set of location signals representing, on said fingerprint image, locations of the picture elements given said relative existence probabilities, respectively;

    existence probability memory means for memorizing practical existence probabilities of said position at the picture elements on said fingerprint image to produce practical existence probability signals representative of the memorized practical existence probabilities, respectively; and

    calculation circuit means coupled to said accessing means and said existence probability memory means for successively and statistically calculating, as said parameters, the practical existence probabilities for said picture elements on said fingerprint image, said practical existence probabilities having a maximum value at the location indicated by the selected one of said location signals;

    said position determining means being coupled to said existence probability memory means to determine said position of the core from said parameters memorized in said existence probability memory means.

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