ISO/TS 22028-5:2023

Overview

ISO/TS 22028-5:2023 is a technical specification developed by ISO’s Technical Committee 42 (Photography) to address the need for standardized high dynamic range (HDR) and wide colour gamut (WCG) encoding for digital still images. As the industry transitions to digital workflows and consumer demand for HDR/WCG content and displays grows, ISO/TS 22028-5:2023 defines compatible colour image encodings, essential and optional metadata, as well as reference viewing conditions. This standard is designed to enable accurate storage, manipulation, transmission, and display of HDR/WCG images, supporting consistency across photography, graphic technology, and digital imaging industries.

Key Topics

• HDR/WCG Colour Image Encodings

  • Defines baseline and extended encodings for digital still images.
  • Baseline encoding ensures broad compatibility, while extended encoding supports advanced workflows.

• Colour Primaries and White Point

  • Specifies standard RGB primaries and D65 white point in line with ITU-R BT.2100-2 and SMPTE ST 2113 (P3-D65).

• Transfer Functions

  • Supports both Hybrid Log-Gamma (HLG) and Perceptual Quantizer (PQ) transfer functions, as recommended by leading HDR/WCG ecosystems.

• Reference Viewing Environment

  • Establishes standard viewing conditions (illumination, surround, display characteristics) for consistent image appearance.

• Metadata Requirements

  • Mandates inclusion of coding-independent code points (CICP) and other metadata to document colour characteristics, reference displays, content colour volumes, and scene-referred states.

• Colour Mapping and Tone Mapping

  • Outlines approaches for rendering encoded images to different displays, ensuring faithful reproduction across diverse hardware and environments.

Applications

ISO/TS 22028-5:2023 supports a wide range of applications in the digital imaging ecosystem:

• Photography and Professional Imaging

  • Enables camera manufacturers, software developers, and content creators to encode and process still images with richer dynamic range and more saturated colours.

• Digital Content Archiving

  • Supports archival workflows requiring accurate colour encoding, scene-referred metadata, and preservation of highlight and shadow detail.

• Media and Content Distribution

  • Assures content creators and distributors that HDR/WCG still images maintain fidelity across various devices and platforms by describing colour volumes and display characteristics via metadata.

• Display Technology and Calibration

  • Facilitates the calibration of HDR-capable displays and ensures accurate reproduction according to industry-standard reference conditions.

• Graphic Arts and Printing

  • Provides a basis for accurate digital image interchange in editing, proofing, and pre-press workflows that require extended colour gamuts.

• Software Development

  • Guides image format designers and software engineers implementing HDR/WCG support within image file formats and editing tools.

Related Standards

The implementation of ISO/TS 22028-5:2023 is closely linked to several foundational standards in photography, broadcasting, and digital imaging:

• ISO 22028-1:2016

  • Architecture and requirements for extended colour encodings.

• ITU-R BT.2100-2

  • Image parameter values and transfer functions for HDR television.

• ISO/IEC 23091-2 / ITU-T H.273

  • Coding-independent code points for video signal identification.

• SMPTE ST 2113

  • Colorimetry of P3 Color Spaces, widely used for reference displays.

• ISO/IEC 23000-22 / MIAF

  • File format integration for advanced HDR profiles and metadata storage.

ISO/TS 22028-5:2023 is essential for organizations and professionals seeking reliable HDR/WCG encoding for digital still images. By providing clear definitions, interoperability guidelines, and practical metadata requirements, this standard is a key resource for advancing high-fidelity digital imaging and ensuring seamless workflow integration across the photography and graphic technology sectors.