Overview
ISO 22028-2:2013 specifies the Reference Output Medium Metric RGB (ROMM RGB) - a family of extended-gamut, output-referred RGB colour image encodings for digital still-picture imaging systems. ROMM RGB is designed so images can be stored, manipulated, transmitted, displayed, or printed without the gamut limitations of sRGB or the complications of encodings that require negative RGB coordinates. The standard defines three precision levels: 8‑, 12‑ and 16‑bits per channel, and includes requirements for the reference viewing environment and reference medium.
Key topics and technical requirements
- Extended-gamut output-referred encoding: ROMM RGB supports a wide colour gamut suitable for professional imaging and print workflows.
- Image state and encoding precision: Defines output-referred image state and quantization options (8/12/16 bits/channel) to suit different storage and processing needs.
- Reference viewing environment and medium: Specifies how images relate to a defined viewing environment and reference medium (important for predictable reproduction).
- Colour component transfer function and transforms: Includes the ROMM RGB encoding and its inverse transformation to/from device-independent colourimetry.
- Interoperability considerations: Guidance for conversion to video RGB and for inclusion in colour-managed pipelines (e.g., ICC profiles).
- Normative references and terms: Uses established colorimetry and profile architecture standards (see Related Standards).
Note: ISO 22028-2 documents informative annexes (selection guidance and conversion notes) to support practical implementation.
Applications
ROMM RGB is intended for workflows that require preserving a wide output gamut through storage, editing and interchange, such as:
- Professional photography - preserving saturated colours (e.g., logos, vivid prints) across retouching and prepress.
- Printing and prepress - accurate handoff from digital files to print targets without forced gamut clipping.
- Image processing and archiving - high-precision master files for long-term storage and future reproductions.
- Software and firmware for digital cameras, scanners, and editing tools - where a standard extended-gamut output encoding improves interoperability.
Who uses this standard
- Photographers and retouchers requiring extended-gamut masters
- Print service providers and color-managed prepress houses
- Software developers (image editors, RAW converters) and hardware manufacturers (scanners, printers)
- Colour scientists and imaging system integrators building predictable reproduction pipelines
Related standards
- ISO 22028-1 - Architecture and requirements for extended colour encodings
- ISO 22028-3 (TS) - Reference Input Medium Metric RGB (RIMM RGB)
- ISO 15076-1 - ICC profile architecture (colour management interoperability)
- ISO 11664-1 - CIE standard colorimetric observers
Keywords: ISO 22028-2, ROMM RGB, extended gamut, output-referred RGB, colour image encoding, colour management, ICC profile, professional photography, digital imaging workflows.
