Algorithm

Ankheg
2010-10-18
2013-05-22
  • Ankheg

    Ankheg - 2010-10-18

    Hi there, I'm looking around at different fingerprinting algorithms, but I'm
    not familiar with .net so I could easily miss things in your code. I'm
    curious, is this a straight-forward bozorth3 implementation? And if not, how
    does it differ?

    Thanks!

     
  • Anonymous - 2010-10-18

    HI Bioster,

    Both SourceAFIS and Bozorth3 use the same concept of compatible edges

    between minutiae, but the underlying implementation is totally different which

    gives both algorithms different performance and accuracy characteristics.

    Extractors use many common concepts, but they differ significantly in others.

    Most notably, SourceAFIS constructs fingerprint skeleton and performs error

    correction on the skeleton while Bozorth3 extractor (MINDTCT).goes straight

    from binarized image to minutiae.

    Kind Regards,

    Robert

     
  • Aditya Gandhi

    Aditya Gandhi - 2012-03-25

    Dear Robert,

    I'm working on the scoring algorithm for fingerprint matching as a part of my
    degree. Could you please explain to me how sourceAFIS calculates the final
    score to decide whether the probe and the candidate fingerprints are a match?

    Is there an intermediate step, where the software has a set of matching and
    non-matching minutia points, using which it then generates a final score?

    Thanks,

    Aditya

     
  • Robert Važan

    Robert Važan - 2012-03-25

    Hi Aditya,

    SourceAFIS has complicated multi-factor scoring function. I don't remember all
    the details. You would do best to take a look into the sources. I am sure
    there's intermediate minutia pairing information.

    Kind Regards,

    Robert

     
    • krishna

      krishna - 2013-04-18

      I am doing research in finger print recognition methods. Can you suggest the titles for the alogirthms used in AFIS to know more about that algorithms. Do you have any patents for those algorithms in AFIS.

       
      • Robert Važan

        Robert Važan - 2013-04-18

        Hi Krishna,

        I don't hold any patents. SourceAFIS algorithms are quite unique, but they fall into some broad categories. Extractor uses smoothing, binarization, and thinning. Matcher is a global minutia matcher that builds minutia tree similar to the one Bozorth3 builds.

        Kind Regards,
        Robert

         
  • Aditya Gandhi

    Aditya Gandhi - 2012-03-26

    I am going through the sources but am finding it difficult to pinpoint to this
    part of the code -- once the matching minutiae pairs have been identified (and
    the non-matching ones) using any number of algorithms, how is the final score
    generated in Afis.Verify?

    It would be of great help even if you would point me to the source file for
    this, if not the algorithm itself.

    Much appreciated,

    Aditya

     
  • Robert Važan

    Robert Važan - 2012-03-26

    Hi Aditya,

    Check out classes MatchAnalysis and MatchScoring.

    Kind Regards,

    Robert

     
  • krishna

    krishna - 2013-04-18

    Do you have any patent rights for the methods used in AFIS. Want to know the titles of the algorithms

     
    • Robert Važan

      Robert Važan - 2013-04-18

      See above for my reply to your previous question.

       
  • YungLung

    YungLung - 2013-05-17

    Hi,Robert!
    SourceAFIS works very well.
    I am interest in a further studying at it.Can you tell me how multi_stage matching works? Or give me some paper about it ?
    And I wonder how the verify score comes out?
    Waiting for your reply.
    Best Regards
    YungLung

     
  • Robert Važan

    Robert Važan - 2013-05-17

    Hi YungLung,

    multi-stage matching simply means applying fast inaccurate algorithm first and slow accurate algorithm second to combine benefits of both. SourceAFIS score function is rather complicated. You will have to take a look into the source code to find out more about score calculation.

    Kind Regards,
    Robert

     
    • YungLung

      YungLung - 2013-05-18

      Hi Robert,

      Can you tell me what do MatchAnalysis.pairCount , correctTypeCount ,supportedCount , pairFraction, and edgeCount mean in the Java sourcecode?

      Best Regards
      YungLung

       
  • Robert Važan

    Robert Važan - 2013-05-19

    Hi YungLung,

    from my memory:

    pair count = number of paired minutiae
    correct type count = like above, but restricted to minutiae of matching type (ending, bifurcation)
    supported count = minutiae that have more than one edge leading to them
    edge count = edges connecting paired minutiae
    pair fraction = pair count / minutia count

    Kind Regards,
    Robert

     
    • YungLung

      YungLung - 2013-05-19

      Hi Robert,
      Thank you for your reply
      But I still wonder which fingerprint feature is used in SourceAFIS?

      Best Regards,
      YungLung

       
    • YungLung

      YungLung - 2013-05-19

      Please ignored my last two questions

      1 Most algorithm use ridge ending and ridge bifuraction as the minutiae,the same SourceAFIS?Or more than these two?
      2 pair count= number of paired minutiae ,does paired minutiae means one from probe ,another from candidate?
      3 what does edge means?Is it a EdgeShape which measured by length,referenceAngle and neighborAngle?By the way ,what do referenceAngle and neighborAngle mean?

       
  • YungLung

    YungLung - 2013-05-19

    I mean used in the extraction

     
  • Robert Važan

    Robert Važan - 2013-05-19

    Hi YungLung,

    what do you mean by feature? The only features of the fingerprint used are minutiae. Ridges are not preserved in the template.

    Kind Regards,
    Robert

     
  • YungLung

    YungLung - 2013-05-19

    Hi Robert,
    I found in MinutiaType 0 stands for ending ,1 stands for bifuration,and what for 2?

    Best Regards,
    YungLung

     
  • YungLung

    YungLung - 2013-05-19

    Hi Robert,
    The feature mean macro feature,such as arch ,tented arch,whorl ……Dose them used during the extraction ?
    And does SourceAFIS classify the fingerprint before the matching to improve the matching speed?
    Best Regards
    YungLung

     
  • YungLung

    YungLung - 2013-05-19

    Hi Robert
    Another question for how SourceAFIS record a minutiae‘s location?Where the (0,0)on a fingerprint image?
    Thank you for your patient reply
    Best Regards
    YungLung

     
  • Robert Važan

    Robert Važan - 2013-05-19

    Hi YungLung,

    1. I don't remember what's minutia type 2, but I am sure there's a descriptively named enum somewhere in the source code.
    2. SourceAFIS doesn't classify fingerprints at all.
    3. SourceAFIS internally uses cartesian coordinate system that historically uses Y axis oriented upwards, i.e. (0,0) point is in the lower left corner. This is intended to simplify angle calculations. Y axis is inverted on input/output (when importing images or ISO templates).

    Kind Regards,
    Robert

     
  • peraperic

    peraperic - 2013-05-21

    Hi Robert,

    I just wanted to ask you if you use any kind of segmentation algorith in your application.

    Regards,
    Pera Peric

     
  • Robert Važan

    Robert Važan - 2013-05-22

    Hi Pera Peric,

    SourceAFIS cannot segment multi-finger images, but it does segment single-finger images into fingerprint area and background area. SourceAFIS does this primarily by clipping off low-contrast areas.

    Kind Regards,
    Robert

     

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