Overview
ISO/IEC 19794-9:2007 - "Information technology - Biometric data interchange formats - Part 9: Vascular image data" specifies a standardized image interchange format for human vascular biometric images (for example, back-of-hand, palm and finger/vein images). The standard defines attributes, a data record format (VIR - Vascular Image Record), a sample record and conformance criteria to enable the exchange of raw or processed vascular images between devices and software from different vendors. It is designed to support interoperability and algorithm flexibility by exchanging captured image data rather than proprietary templates.
Key topics and technical requirements
- Data model & conformance
- Defines a Vascular Image Record (VIR) with mandatory and optional fields.
- Conformance requires the ability to encode/decode vascular image data and associated parameters to enable interoperable exchange and extraction.
- VIRs are intended to be embedded in a CBEFF-compliant Biometric Data Block (per ISO/IEC 19785-1).
- Data conventions
- Big-endian byte and bit ordering (most significant byte/bit first).
- Raster scan sequence: left-to-right, top-to-bottom.
- Image capture & representation
- Spatial resolution: not mandated as a single minimum (must be represented in pixels per centimetre); choice depends on modality (finger vs palm).
- Gray scale depth: dynamic range of at least 128 gray levels; at least 1 byte (8 bits) per pixel providing at least 7 bits of useful intensity.
- Illumination: typically near-infrared (~700–1 200 nm); images may be reflectance or transmission based; multiple wavelengths allowed for background masking.
- Pixel aspect ratio: default 1:1; non-square pixels must be declared.
- Projection & geometry: images must be orthographic to the body area; major optical distortions must be corrected prior to VIR creation.
- Image storage & compression
- Supports compressed and uncompressed image specs; normative references include common image coding/compression standards (e.g., JPEG, JPEG 2000, lossless compression standards) for interchange.
- Header and metadata
- Detailed header fields carry scan parameters, imaging area, standard pose and coordinate system definitions to ensure consistent interpretation.
Applications and users
- Who uses it
- Biometric device manufacturers (finger/palm/hand vein sensors)
- Software developers and algorithm vendors (matching, verification)
- System integrators, government agencies, border control, enterprise access control, healthcare and forensic labs
- Standards and compliance teams procuring interoperable biometric systems
- Practical benefits
- Vendor interoperability: exchange raw or processed vascular images between systems
- Algorithm portability: allow different matching algorithms to operate on common image data
- Flexibility for research and development: retain image detail to enable improved accuracy and multimodal fusion
Related standards
Keywords: ISO/IEC 19794-9:2007, vascular image data, vascular biometrics, biometric data interchange formats, finger vein, palm vein, VIR, CBEFF, image capture requirements, interoperability.
