Design Nomenclature / Color
CIE XYZ
Also called XYZ, CIE 1931, tristimulus
The 1931 foundation space: three imaginary primaries derived from color-matching experiments and chosen so that Y carries luminance and every real color takes positive coordinates. Nothing here is designed for human use — it is the hub every other space converts through, and the reason a Lab value means the same thing on two continents.
Not to be confused with
- CIELABA device-independent opponent space — L* for lightness, a* green to red, b* blue to yellow — built so equal numeric distances approximate equal perceived differences. Its polar form, LCh, restates a* and b* as chroma and hue angle. Both inherit a documented flaw: the blue region bends, so hue drifts along a ramp that should hold it.
- RGBAn additive model addressing color as amounts of red, green, and blue primaries. RGB by itself specifies nothing absolute: the same triplet means different colors on different devices until a space pins down the primaries, the white point, and the transfer curve. RGB without a profile is a coordinate with no map.