ISO 20677:2019

Overview

ISO 20677:2019 - Image technology colour management - defines extensions to the ICC profile architecture, profile format and data structure. Based on ISO 15076-1, this standard expands profile specifications and profile connection mechanisms to enable greater flexibility and functionality in colour management workflows. It sets minimum structural and operational requirements for writing and reading ICC profiles while preserving backwards compatibility with ISO 15076-1 profiles. Domain-specific workflow restrictions and additional requirements are specified in ICC-approved interoperability conformance specification (ICS) documents.

Key topics and technical requirements

• Extended profile architecture: Adds new profile classes and connection space concepts (e.g., spectral and bi-spectral PCSs, BRDF and directional viewing connections, multiplex connection spaces).
• Profile header and tag table enhancements: Defines extended header fields and detailed tag table structure. Header examples include profile size, preferred CMM type, profile version/sub-version, profile/device class, data colour space, PCS, date/time, profile file signature, platform, profile flags, manufacturer/model, rendering intent, PCS illuminant, profile ID, spectral PCS fields, and MCS.
• Expanded basic data types: Introduces and refines types such as float16Number, float64Number, azimuthNumber, horizontalNumber, verticalNumber, zenithNumber, spectralRange, tintArray, and sparse matrix encodings (including a new sparseMatrixEncodingType).
• MPE/MCS and BRDF: The Multi-Profile Extensions (MPE) type is expanded; spectral and parameter-based BRDF connections and MCS (Multiplex Connection Space) encodings are specified for complex device and material representations.
• Conformance and backward compatibility: CMMs (colour management modules) compatible with ISO 20677 profiles remain backwards compatible with ISO 15076-1 profiles; conformance rules and precedence of tag usage are defined.

Practical applications and who uses it

This standard is intended for practitioners implementing advanced colour workflows and profile formats, including:

• Colour scientists and researchers working with spectral, directional or BRDF-based colour data
• CMM and imaging software developers building ICC profile readers/writers
• Device manufacturers (printers, displays, scanners) requiring extended device encoding and spectral profile support
• Prepress, photography and digital publishing professionals needing higher-fidelity colour reproduction and interoperable profiles
• Standards bodies and integrators creating ICC-based interoperability conformance specifications (ICS)

Related standards

• ISO 15076-1 - the base ICC profile architecture and profile format (all definitions remain in force unless superseded)
• ICC interoperability conformance specifications (ICS) - domain-specific workflow requirements referenced by ISO 20677

Keywords: colour management, ICC profiles, image technology, profile format, spectral PCS, BRDF, colour encoding space, CMM, ISO 15076-1, profile header, tag table, multiplex connection space.