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Biometric interoperability

Interoperability is crucial when dealing with mobile biometric identification.

Mobile ID devices are commonly known as portable biometric acquisition stations used to capture one or more biometric samples such as fingerprint, facial and iris from a subject.

Currently mobile ID devices have been very popular in several government and industry applications, but one problem that the users encounter is lack of common interoperability in order to connect and search other systems without regard to existing dissimilarities between vendor systems.

Mobile ID devices have been applied for a variety of non-stationary applications where access to traditional implementation of full-sized live scan fingerprint readers and photo capture stations with setups adhering to standards are not possible.

There is a great need for guidelines for the capture, security and transmission of mobile identification data that can be interoperable with similar and dissimilar systems. The guidelines that can lead to international standards for mobile ID units and promote interoperability and data exchange.

Currently, government applications are major drivers in setting international standards and institutions such as NIST (National Institute of Standards & Technology) and ISO/IEC (International Organization for Standardization/International Electrotechnical Commission) are the vehicles of writing relevant best practice recommendations and standards.

Participation of all countries is required and South Africa is well represented in the above organisations through the South African Bureau of Standards. The compatibility of a mobile ID device for enrolment, identification or verification functions can be tailored to the government or industry applications based on different SAP (Subject Acquisition Profile) levels.

ANSI/NIST guidelines define parameters concerning the content, format and units of measurement for the exchange of biometric sample information such as fingerprint scanning resolution or pixel distances between facial features. Processing and exchanging biometric data captured from a Mobile ID device should be compliant with ANSI/NIST-ITL standards for transmission and seamless exchange.

Mobile ID fingerprint capture devices

A very high quality enrolment image must be acquired in order to achieve acceptable matcher performance. ANSI/NIST-ITL type 14 record must be used for capturing more than a single finger. An initial quality assessment should be done on the mobile device during the capture process applying NFIQ algorithm (NIST Fingerprint Image Quality).

To achieve high interoperability across dissimilar systems, the mobile ID fingerprint capture device should transmit the fingerprint image(s) and enable the finger minutiae to be extracted and processed on the system where the matching will take place. However, sometimes minutiae-based approach may not be acceptable in some cases.

Mobile ID facial image capture devices

In some circumstances, capturing facial images may be of more value than taking fingerprints. The face image quality should be done to provide feedback to the operator during the capture process. Face Capture Requirements address capture distance, capture device controls, capture device frame rate photo image format, capture device image size and aspect ratio, capture device sensitivity and facial image compression.

For the exchange of facial images the SAP levels the ANSI/NIST-ITL 1-2007 Type 10 logical record standard should be used to encode compressed image files and other metadata.

Mobile ID iris image capture

The mobile ID iris capture device must be able to measure the iris image quality preferably during the capture process and on the device. The minimum acceptable iris image diameter is 140 pixels and increases with the SAP levels up to 210 pixels.

In order to support interoperability ANSI/NIST-ITL Type 17 records should be used with raw images conforming to ISO 19794-6 rectilinear image standards.

Image quality requirements differ for each biometric function (enrolment, identification and verification). Severe security risk levels require aggressive image size and quality requirements independent of technology availability.

Continuous work is being done to produce guidelines and standards to meet the stringent requirements of governments and industry.

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