CIE (1931) XYZ colour space

The CIE 1931 XYZ colour space (also known as CIE 1931 colour space) was one of the first mathematically defined colour spaces and was adopted by the International Commission on Illumination (CIE) as its standard method.

  • The CIE XYZ colour space was the first comprehensive method able to systematise the relationship between colour stimuli and human colour perception.
  • In an experimental situation, the CIE XYZ colour space is able to match any colour an observer sees with a known mixture of wavelengths of light.
  • The foundation of the CIE XYZ colour space is the ability to identify the precise mixture of wavelengths of light needed to stimulate cone cells to produce any colour experience within the visible spectrum.
  • Viewed diagrammatically the CIE XYZ colour space takes the form of a graph showing a volume of colour corresponding with every wavelength in the visible spectrum. The location of every colour is determined in relation to the x and y axes of the graph. The two axes are used to identify the coordinates for each colour within this two-dimensional vector space.
  • The coordinates themselves are derived from tristimulus colour values.
  • With the development of the CIE XYZ colour space, trichromatic colour models and their corresponding colour spaces provide methods for anticipating and managing colour reproduction in every applicable field and type of technology.
  • In terms of colour management, the trichromatic colour theory underpins device-independent additive colour spaces such as the sRGB colour space and the Adobe RGB colour space and device-dependent additive colour models such as RGB, HSB and CMYK and their corresponding colour spaces.

The CIE XYZ colour space serves as a standard reference and underpins more recent colour spaces such as:

  • CIELUV 1976 –  a modification of CIE 1931 XYZ used to display additive mixtures of light more conveniently.
  • CIELAB 1976 –  a more perceptually linear colour space. Perceptually linear means that changes in colour values are directly related to changes in colour appearance.  CIELAB is commonly used for surface colours, but not for mixtures of light.