ISO/IEC 19794-10:2007

Overview

ISO/IEC 19794-10:2007 - "Information technology - Biometric data interchange formats - Part 10: Hand geometry silhouette data" defines a standardized data interchange format for storing, recording and transmitting hand silhouette information inside a CBEFF (Common Biometric Exchange Formats Framework) Biometric Data Block (BDB). The standard specifies the content, formats and units of measurement for hand silhouette data used in verification or identification, while explicitly not mandating any particular matching algorithm. It enables vendor-neutral exchange of hand geometry records (left/right hand, multiple views) for interoperable biometric systems.

Key topics and technical requirements

• Data structure: Hand geometry data is packaged as a CBEFF-compliant Biometric Information Record (BIR) containing a Silhouette BDB and optional security block. CBEFF identifiers specified for this part are Format Owner 0x0101 and Format Type 0x0018.
• Silhouette encoding: Perimeter contours are compressed using Freeman Chain Codes (FCC) - either 8-way (3 bits/direction) or 4-way (2 bits/direction). The standard requires body-centric FCC representation and bit-packed storage with byte padding.
• Record elements: Mandatory and optional items include capture parameters, standardized hand orientation/position metadata, vendor-specific extensions, and one or more Hand Geometry View Records (HGVR).
• Image characteristics: Stored silhouettes should use a 1:1 aspect ratio (±2%), defined coordinate system, closed contours, and a specified starting point/trace direction (counterclockwise) to ensure consistency.
• Low-level rules: Byte order is big-endian (network order). Silhouettes may represent top-view or side-view orientations; left-hand images may need mirroring to the canonical form.
• Interoperability focus: Multiple views per hand are allowed but implementations constrained by storage (e.g., smart cards) should be aware such limits can reduce interoperability.

Applications

• Access control and time & attendance systems where hand geometry is used as a biometric modality
• Biometric enrollment, verification and identification systems that need to exchange templates across vendors
• Secure transmission and storage of hand silhouette data in databases, smart cards, or biometric middleware
• Integration projects aiming to replace proprietary hand-geometry templates with an interoperable format

Who should use this standard

• Biometric system vendors and integrators
• Security architects and identity management teams
• Government and enterprise agencies deploying access control
• Smart card and embedded-system designers handling constrained storage

Related standards

• ISO/IEC 19794 (other parts for fingerprints, face, iris, etc.)
• ISO/IEC 19785-1 (CBEFF data element specification)
• ISO/IEC 19784-1 (BioAPI)

Keywords: ISO/IEC 19794-10:2007, hand geometry silhouette data, biometric data interchange, CBEFF, Freeman Chain Code, HGVR, BDB, hand geometry standard.