Expand description
The aim of the color management extension is to allow clients to know the color properties of outputs, and to tell the compositor about the color properties of their content on surfaces. Doing this enables a compositor to perform automatic color management of content for different outputs according to how content is intended to look like.
The color properties are represented as an image description object which is immutable after it has been created. A wl_output always has an associated image description that clients can observe. A wl_surface always has an associated preferred image description as a hint chosen by the compositor that clients can also observe. Clients can set an image description on a wl_surface to denote the color characteristics of the surface contents.
An image description includes SDR and HDR colorimetry and encoding, HDR metadata, and viewing environment parameters. An image description does not include the properties set through color-representation extension. It is expected that the color-representation extension is used in conjunction with the color management extension when necessary, particularly with the YUV family of pixel formats.
Recommendation ITU-T H.273 “Coding-independent code points for video signal type identification” shall be referred to as simply H.273 here.
The color-and-hdr repository (https://gitlab.freedesktop.org/pq/color-and-hdr) contains background information on the protocol design and legacy color management. It also contains a glossary, learning resources for digital color, tools, samples and more.
The terminology used in this protocol is based on common color science and color encoding terminology where possible. The glossary in the color-and-hdr repository shall be the authority on the definition of terms in this protocol.
Warning! The protocol described in this file is currently in the testing phase. Backward compatible changes may be added together with the corresponding interface version bump. Backward incompatible changes can only be done by creating a new major version of the extension.