ISO/IEC 12089:1997

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

• ISO/IEC 12087-1, -2, -3 (IPI architecture, programming interfaces, IIF-DF)
• ISO/IEC 8824 (ASN.1), ISO/IEC 8825 (BER) and ISO/IEC 8825-2 (PER)
• ISO/IEC 8632 (CGM/metafile)

Keywords: ISO/IEC 12089, Image Interchange Facility (IIF), IIF encoding, ASN.1, BER, PixelFieldEncoding, EncodingRules, image interchange format, image processing standard.