Overview
ISO/IEC 12089:1997 specifies the encoding rules for the Image Interchange Facility (IIF) used within the Image Processing and Interchange (IPI) family (ISO/IEC 12087). The standard defines how IPI‑IIF image data are represented at the encoding level. It reuses ASN.1 syntax (ISO/IEC 8824) and the Basic Encoding Rules (BER, ISO/IEC 8825) but also specifies additional, application-level encoding methods to efficiently represent large Pixel fields when an ASN.1 OCTET STRING carries many values.
Key topics and technical requirements
- ASN.1-based Syntax: The IIF encoding definitions are expressed as an ASN.1 module (IIFEncoding) exposing entities such as PixelFieldEncoding, EncodingRules, UniformEncoding and HierarchicalEncoding.
- BER as Foundation: Encoding of syntax entities conforms to BER (ISO/IEC 8825). The standard explicitly references BER while describing encoding approaches that operate “on top of” BER decoding/encoding tools.
- Pixel field optimizations: Because BER can impose tag/length overhead for large pixel arrays, the standard provides additional methods for packing Pixel fields (e.g., OCTET STRING interpreted as multiple values).
- Byte-order / octet swapping: PixelFieldEncoding includes byte-order-swapped semantics to handle octet significance and machine dependencies that must be managed at the application level.
- EncodingRules variants:
- UniformEncoding - describes consistent packed encodings with iteration and alignment constructs to indicate padding and multi‑dimensional iteration.
- HierarchicalEncoding / ComplexEncoding - supports nested or heterogeneous encodings (e.g., mixed bit-width integers and floating point components) and multi-level alignment (e.g., octet boundaries).
- IterationAndAlignment and Padding: Mechanisms to express explicit or implicit iteration over image dimensions and where padding bits occur in packed encodings.
- Constraints: Pixel-values (represented as BITSTRING) must match the array dimensions declared by the associated image structure.
Practical applications and users
ISO/IEC 12089 is aimed at implementers and integrators working with the IPI/IIF image interchange format:
- Software developers building imaging libraries, IIF gateways, or image interchange tools that encode/decode IIF-DF data.
- System integrators and vendors of image processing platforms who need interoperable image exchange.
- Standards bodies and archival/metadata specialists who reference consistent encoding rules for long-term storage and interchange.
- Use cases include high-volume image transfer, multi-component/heterogeneous image payloads, and systems requiring compact, interoperable packed encodings.
Related standards
Keywords: ISO/IEC 12089, Image Interchange Facility (IIF), IIF encoding, ASN.1, BER, PixelFieldEncoding, EncodingRules, image interchange format, image processing standard.
Open preview (PDF)Information technology — Computer graphics and image processing — Encoding for the Image Interchange Facility (IIF)
