Overview
ISO/IEC 23008-12:2025/Amd 1:2025 is an amendment to ISO/IEC 23008-12:2025 - Image File Format, part of the series "Information technology - High efficiency coding and media delivery in heterogeneous environments." This amendment adds explicit support for tone-map derivation (gain maps) and a set of metadata, tiling and stereo-related technologies to improve interoperability for HDR/SDR conversion, tiled image delivery and stereoscopic content.
Key topics and technical requirements
- Tone-map derived image items: Introduces new item types - tone-map derived image item (tmap), base image item and gain map image item. Tone-map derivation follows ISO 21496-1 (gain map metadata for dynamic range conversion) enabling defined SDR↔HDR transforms.
- Normative references: Adds ISO/CIE 11664-3, ISO/CIE 11664-4 (colorimetry/CIE tristimulus and Lab*) and ISO 21496-1 for gain maps.
- Overview images & image pyramids: Defines overview images produced by binning base images, rules for tiling, padding incomplete tiles with zeros and optional use of the clean-aperture ('clap') property. Overview images can be stacked into an image pyramid entity group.
- Constrained tile access: New ConstrainedExtentsGridProperty ('cexg') indicates that each extent corresponds to independently decodable, contiguous byte-range image tiles; includes fields for tile width/height and optional per-tile decoder config.
- Camera metadata placement: CameraExtrinsicMatrixProperty and CameraIntrinsicMatrixProperty must precede transform properties because descriptive properties after transforms are ignored. Intrinsic matrix calculations reference the image output dimensions after transforms.
- Stereo metadata: Adds DisparityAdjustmentProperty ('dadj') (units = 1/10 000 image widths) and StereoAggressorsProperty ('stag') to describe potential viewer discomfort with severity scale (0 = unknown, 1–42 mild, 43–84 medium, 85–127 high).
- Branding and identifiers: Several properties require the file to signal the 'unif' brand in FileType or ExtendedTypeBox when associated with entity groups; replaces use of "item_ID" with "identifier value".
Applications
- HDR/SDR conversion pipelines using gain maps for backward/forward compatible tone-mapping.
- Image viewers, editors and decoders that require byte-range access to tiles (map services, large image viewers).
- Media servers and streaming platforms delivering tiled or multi-resolution image pyramids.
- Camera firmware, post-production tools and content pipelines that embed camera intrinsics/extrinsics and stereo health metadata.
- VR/AR and stereoscopic workflows that need explicit disparity adjustment and stereo aggressor detection metadata.
Who should use this standard
- File format implementers, codec and image library developers
- Camera and imaging device manufacturers
- Streaming/media platform engineers and CDN integrators
- Post-production and HDR content creators
- VR/AR/stereo content tool vendors
Related standards
- ISO/IEC 23008 series (image/video coding and delivery)
- ISO 21496-1 (gain map metadata for image conversion)
- ISO/CIE 11664-3 and ISO/CIE 11664-4 (colorimetry)
Keywords: ISO/IEC 23008-12:2025/Amd 1:2025, Image File Format, tone-map derivation, gain map, overview images, ConstrainedExtentsGridProperty, HDR, SDR, tiled images, stereo aggressors, disparity adjustment.
Open preview (PDF)Information technology — High efficiency coding and media delivery in heterogeneous environments — Part 12: Image File Format — Amendment 1: Support for tone map derivation and other technologies
