Color Space

A color space is a subspace of the absolute CIE XYZ color space that includes all possible, human-visible color coordinates (therefore makes human visual perception mathematically tractable). CIE XYZ is based on the RGB color model and consists of an infinite three-dimensional space but characterized (and limited) by the xyz coordinates of five particular points: the Black Point (pure black); the White Point (pure white); Reddest red color (pure red); Greenest green color (pure green); and Bluest blue color (pure blue). All these coordinates define an XYZ matrix. The color spaces are submatrices (minors) of the XYZ matrix. The absolute color space is device independent while the color subspaces are mapped to each individual device. For a more detailed introduction see: A color space consists of primaries (gamut), transfer function (gamma), and matrix coefficients (scaler).

Color primaries
: the gamut of the color space associated with the media, sensor, or device (display, for example).
Transfer characteristic function
: converts linear values to non-linear values (e.g. logarithmic). It is also called Gamma correction.
Color matrix function
(scaler): converts from one color model to another. RGBYUV; RGBY'CbCr; etc.

The camera sensors are always RGB and linear. Generally, those values get converted to YUV in the files that are produced, because it is a more efficient format thanks to chroma subsampling, and produces smaller files (even if of lower quality, i.e. you lose part of the colors data). The conversion is nonlinear and so it concerns the "transfer characteristic" or gamma. The encoder gets input YUV and compresses that. It stores the transfer function as metadata if provided.

The CINELERRA-GG Community, 2021