Windows Biometric Framework and images in ANSI-INCITS 381 interchange format...

2012-11-14
2012-11-19
  • J-B Herbert

    J-B Herbert - 2012-11-14

    Hi, I want to use SourceAFIS but have difficulties aquiring images of fingerprints from hardware.
    What I have immediately on hand is a TouchChip built-in in a Dell Laptop.

    Since I didn't found any API to aquire images from that device (and I also want to support multiple scanner types), I tried the Windows 7 "Windows Biometric Framework" (WBF) to obtain images. I finally succedded obtaining a raw image data in an "Ansi-INCITS 381 image-based interchange format" file. However I can't find anywhere how to convert that format to one that will be suitable for SourceAFIS.

    Does anyone explored the Ansi-381 file type ? Does anyone can give me places to go to obtain images in another format from a TouchChip unit ?

    Any help will be greatly appreciated !

     
  • Robert Važan

    Robert Važan - 2012-11-14

    Hi,

    SourceAFIS has limited support for biometric standards. It expects plain images on input. You will need a conversion library. There are commercial packages that can read/write various standard formats. You can also try the free implementation from NIST that includes support for INCITS 381:

    http://www.nist.gov/itl/iad/ig/biomdi.cfm

    Kind Regards,
    Robert

     
  • J-B Herbert

    J-B Herbert - 2012-11-16

    Thanks for the information. I've looked at the code and it does provide part of the format (headers, etc.) but I didn't found information about the image format itself. And also the headers doesn't match exactly to what I have (so it makes me wonder if it is a fully compliant INCITS 381 that I have).

    I decided to go "like the old days" and tried to make sense of what was in the file manually. It was easier than I thought! For those who may be interrested, it may or may not be the case with your hardware but here it is :

    Header was 136 bytes
    Information about width and height were a few bytes before the end of header (in two 16 bit unsigned integers)
    For my hardware, it was 186x270 pixels.
    The payload (everything after the header) was simply each pixels not compressed in any way and 8 bit grayscale per pixel.

    Hope it helps someone...

     

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