ISO/IEC 19794-2 is an international fingerprint template standard standard that was created in order to achieve interoperability between different fingerprint recognition systems. In other words, it allows fingerprint templates generated by different vendors to be used in the same system for fingerprint enrollment and matching. This standard specifies the location and formatting of fingerprint minutiae template.

Why do we need ISO/IEC 19794-2 fingerprint interoperability?

There are 2 main reasons for storing fingerprint templates in an ISO/IEC 19794-2 format:

1. Interoperability is required when different subsystems from different biometric vendors are used.
Let’s look at an example. In order to enroll users you use Fingerprint Scanner A. The enrolled fingerprint image is converted into a fingerprint template using fingerprint algorithm from vendor X and stored in the Database.

During fingerprint authentication, the fingerprints are captured using Fingerprint Scanner B. These fingerprints are converted into fingerprint templates using Fingerprint Algorithm from vendor Y.

Now, the problem is, in order to match the authentication fingerprint (generated by algorithm Y) to the enrolled fingerprint (generated by algorithm X) you need some sort of industry standard.

Interoperability enables the template generated by fingerprint algorithm X to be compared with the template generated by fingerprint algorithm Y. That is, even though fingerprint templates X & Y are from different vendors as long as they are in ISO/IEC 19794-2 format we can compare them to see if a match is found.

2. You might be using only a single vendor’s fingerprint algorithm for enrollment and authentication. In this case you can enroll fingerprints using the vendor’s proprietary format (instead of ISO ). However, if after few years you decide to change vendors, the proprietary templates will not work with any other fingerprint algorithm. Hence the fingerprint database that you have created will be of no use and you will have to re-register all the users again.

Why not store the raw fingerprint images?

You might ask why not just store the raw fingerprint images of all the enrolled users. That way if you change fingerprint vendors you can easily convert the raw fingerprints into fingerprint templates and start using it and there would be no need to re-register users. There are multiple drawbacks with storing raw images

1. Raw fingerprint images take up much more space then fingerprint templates. A Raw fingerprint image takes up about 250KB space where as a fingerprint template only takes up about 500 bytes of space.

2. Storing Raw fingerprint images create lots of privacy concerns. Storing a fingerprint template is much more safer. Even if the fingerprint templates are compromised, it is not possible to generate a fingerprint image from a template. However, you would not want the raw fingerprints to be accessed by anyone.

Real World Example

We were contacted by a client recenty informing us that they are using a Biometric Point of Sale System and they would want us to create a fingerprint de-duplication engine for them.  De-duplication ensures that when you are registering a person only unique fingerprints are registered. We were delighted to hear that the Biometric Point of Sale System that the client was using stores data in various ISO formats, including  ISO/IEC 19794-2 format. However when we took a closer look at their fingerprint database we realized that it was encrypted and the vendor would not provide us (or the client) with the decryption key. Unfortunately, we or anyone else could not help this client. This is one of the rare cases where the client ensured that they were storing fingerprints in ISO/IEC 19794-2 format could not use the registered fingerprints for other application.