ISO/IEC 23000-22:2019

Overview

ISO/IEC 23000-22:2019 specifies the Multi‑Image Application Format (MIAF), a constrained, interoperable profile of the High Efficiency Image File (HEIF) container (ISO/IEC 23008‑12). MIAF packages coded images, image groups and sequences, alpha planes and associated metadata together in HEIF files and defines the normative behaviour of a MIAF reader and MIAF renderer. The specification is intentionally extensible to allow forward compatibility while simplifying HEIF options for reliable cross‑platform interoperability.

Key topics and technical requirements

• HEIF constraints: MIAF imposes additional constraints on the HEIF file format to reduce optionality and ensure consistent parsing and rendering.
• Alpha plane formats: Defines specific supported alpha (transparency) plane encodings for compositing and overlays.
• Profiles and levels: Specifies supported coding formats through a set of profiles and levels to guarantee decoder capability interoperability.
• Metadata formats: Requires particular metadata (including content light level and mastering display colour volume properties) and metadata formats for consistent image presentation and HDR workflows.
• Brands and file signalling: Introduces application brands (e.g., progressive, animation, burst capture, fragmented alpha video, common media fragmented) and conventions for file extensions and application signalling.
• Reader and renderer behaviour: Normative rules for how MIAF readers parse files and how renderers present master, derived, thumbnail and auxiliary images.
• Extensibility rules: Rules for extending MIAF to add new coding formats, profiles, levels or metadata while preserving forward compatibility.
• Permissive coexistence: Allows other data (additional coding formats, metadata, derived images) to be present while maintaining clearly defined interoperability points.

Applications and who uses it

• Device manufacturers (camera and smartphone OEMs) for reliable storage of multi‑image content (bursts, HDR captures, layered images).
• Imaging and photo‑editing software vendors to ensure consistent import/export and rendering of HEIF‑based collections.
• Cloud storage and media delivery services to standardize processing, thumbnails, and metadata handling.
• Playback and compositing engines (browsers, OS image libraries, video players) that must render multi‑image assets, animations and alpha overlays.
• Content workflows requiring HDR metadata, derived images, and grouped image sequences (e.g., burst-to-HDR workflows, animated images).

Related standards

• ISO/IEC 23008‑12 - HEIF (base format MIAF constrains)
• ISO/IEC 14496‑12 - ISO base media file format
• Rec. ITU‑T H.265 / ISO/IEC 23008‑2 - HEVC video coding
• Rec. ITU‑T H.264 / ISO/IEC 14496‑10 - AVC video coding
• ISO 16684‑1 - XMP metadata
• ISO/IEC 23000‑19 - CMAF (related media application format)

Keywords: MIAF, HEIF, ISO/IEC 23000‑22:2019, multi‑image application format, MIAF reader, MIAF renderer, profiles and levels, alpha plane, metadata, interoperability.