CIE XYZ is the device-independent hub space used for all color space conversions

Defined by the CIE in 1931, CIE XYZ is grounded in the measured color-matching responses of human observers. Key properties: all spectral colors have non-negative XYZ coordinates; the Y channel corresponds directly to luminance. Every other RGB color space is defined by its relationship to XYZ. Conversions between any two color spaces route through XYZ as an intermediate, so only N matrices (not N²) are needed for N spaces. This hub-and-spoke design underlies the ICC color management system.

Examples

sRGB → Display P3: sRGB → XYZ (via sRGB-to-XYZ matrix), then XYZ → P3 (via XYZ-to-P3 matrix).

Assessment

Why is it useful to have a single connection color space (XYZ) rather than defining direct conversion matrices between every pair of color spaces?