iso 19794-2 fingerprint format

Question

I am using iso 19794-2 fingerprint data format. All the data are in the iso 19794-2 format. I have more than hundred thousand fingerprints. I wish to make efficient search to identify the match. Is it possible to construct a binary tree like structure to perform an efficient(fastest) search for match? or suggest me a better way to find the match. and also suggest me an open source api for java to do fingerprint matching. Help me. Thanks.

Answer 1

The iso format specifies useful mechanisms for matching and decision parameters. Decide on what mechanism you wish to employ to identify the match, and the relevant decision parameters. When you have determined these mechanisms and decision parameters, examine them to see which are capable of being put into an order - with a fairly high degree of individual values, as you want to avoid multiple collisions on the data. When you have identified a small number of data items (preferably one) that have this property, calculate the property for each fingerprint - preferably as they are added to the database, though a bulk load can be done initially. Then the search for a match is done on the calculated characteristic, and can be done by a binary tree, a black-red tree, or a variety of other search processes. I cannot recommend a particular search strategy without knowing what form and degree of differentiation of values you have in your database. Such a search strategy should, however, be capable of delivering a (small) range of possible matches - which can then be tested individually against your match mechanism and parameters, before deciding on a specific match.

Answer 2

Do you have a background in fingerprint matching? It is not a simple problem and you'll need a bit of theory to tackle such a problem. Have a look at this introduction to fingerprint matching by Bologna University's BioLab (a leading research lab in this field).

Let's now answer to your question, that is how to make the search more efficient.

Fingerprints can be classified into 5 main classes, according to the type of macro-singularity that they exhibit.

There are three types of macro-singularities:

• whorl (a sort of circle)
• loop (a U inversion)
• delta (a sort of three-way crossing)

According to the position of those macro-singularities, you can classify the fingerprint in those classes:

• arch
• tented arch
• right loop
• left loop
• whorl

Once you have narrowed the search to the correct class, you can perform your matches. From your question it looks like you have to do an identification task, so I'm afraid that you'll have to do all the comparisons, or else add some layers of pre-processing (like the classification I wrote about) to further narrow the search field.

You can find lots of information about fingerprint matching in the book Handbook of Fingerprint Recognition, by Maltoni, Maio, Jain and Prabhakar - leading researchers in this field.

In order to read ISO 19794-2 format, you could use some utilities developed by NIST called BiomDI, Software Tools supporting Standard Biometric Data Interchange Formats. You could try to interface it with open source matching algorithms like the one found in this biometrics SDK. It would however need a lot of work, including the conversion from one format to another and the fine-tuning of algorithms.

My opinion (as a Ph.D. student working in biometrics) is that in this field you can easily write code that does the 60% of what you need in no time, but the remaining 40% will be:

• hard to write (20%); and
• really hard to write without money and time (20%).

Hope that helps!

Edit: added info about NIST BiomDI

Edit 2: since people sometimes email me asking for a copy of the standard, I unfortunately don't have one to share. All I have is a link to the ISO page that sells the standard.