Overview
ISO 22028-5:2026 is an international standard developed by ISO that addresses extended colour encodings specifically for high dynamic range and wide colour gamut (HDR/WCG) digital still images. It is a part of the ISO 22028 series on photography and graphic technology, focusing on transparent and interoperable colour image storage, manipulation, and interchange. This standard defines consistent colour encoding systems, mandatory and optional metadata structures, and the reference viewing environments necessary to ensure consistent appearance and accurate colour reproduction for HDR and WCG still images across diverse platforms.
Key Topics
- HDR/WCG Colour Encodings: The document standardizes both baseline and extended colour encodings suitable for digital image storage, transmission, and display, leveraging widely adopted profiles from ITU-R BT.2100-3.
- Metadata Management: It defines required and optional metadata, including coding-independent code points (CICP), mastering display colour volume (MDCV), content colour volume (CCV), content light level (CLL), HDR reference white luminance, and scene-referred status. This ensures transparency and interoperability across different workflows and viewing devices.
- Reference Conditions: The standard outlines precise reference viewing conditions and display specifications, such as colour primaries (e.g., P3-D65), white point, peak luminance, and black point, allowing consistent viewing experiences for end-users.
- Transfer Functions: Support for both Hybrid Log-Gamma (HLG) and Perceptual Quantizer (PQ) transfer functions allows encoding flexibility for a wide range of image content and legacy compatibility with various HDR/WCG displays.
- Colour Mapping and Conversion: Guidance is provided on the recommended approaches for colour mapping and gamut conversion, ensuring that images are rendered optimally on diverse displays with varying capabilities.
Applications
ISO 22028-5:2026 is of practical value in a broad spectrum of photography, imaging, and graphic technology workflows, including but not limited to:
- Digital Photography: Camera manufacturers and software developers can use the standard to encode and store HDR/WCG image data, ensuring user content takes advantage of increased colour richness and contrast.
- Image Archives: Ideal for cultural heritage, medical, or scientific archives requiring long-term, consistent preservation and retrieval of HDR/WCG digital still images.
- Professional Imaging & Post-Production: Studios, post-processing tools, and graphics professionals benefit from robust colour management when manipulating and exchanging image assets.
- Consumer Electronics: Display manufacturers, including those producing TVs, monitors, and mobile devices, use the standard’s metadata structures and reference conditions to ensure faithful rendering of wide gamut and high dynamic range images.
- Digital Publishing and Printing: Provides a framework for graphic designers and publishers to maintain colour fidelity from digital originals to printed output under defined viewing conditions.
Related Standards
The following standards are closely related to or referenced within ISO 22028-5:2026, supporting its implementation and integration into existing workflows:
- ITU-R BT.2100-3: Image parameter values for high dynamic range television, foundational to HDR/WCG encoding definitions and transfer functions.
- ISO/IEC 23091-2: Information technology-Coding-independent code points for video signal type identification, crucial for interoperable metadata.
- SMPTE ST 2113: Standard for P3 colour primaries, widely adopted in professional display environments.
- ISO/IEC/TR 23091-4: Usage of video signal type code points, providing terminological and usage context for metadata.
- ISO 22028-1: General requirements for extended colour encodings in digital imaging.
Conclusion
By providing standardized HDR and WCG colour encodings along with comprehensive metadata and viewing guidelines, ISO 22028-5:2026 ensures reliable storage, manipulation, and interchange of advanced digital images. Its adoption supports the growth of HDR/WCG ecosystems, enabling creators, manufacturers, and consumers to benefit from richer visual experiences with consistent and predictable colour fidelity.