Color spaces

XYZ

(Tristimulus values)

A color space created by the CIE for color matching functions. It is based on imaginary primary colors and can be used to match all colors in the visible spectrum (demonstrated in the CIE chromaticity diagram).

XYZ was a transformation of CIE RGB color space, ensuring values are all positive and accommodating for luminance equations of CIE photometry.

XYZ values are sometimes referred to as "tristimulus values". The "Y" value is also known as relative luminance.

Example

Note: XYZ is not supported in any devices. The colors shown in this tool only depict colors that are within the sRGB gamut.

How it affects UI design

XYZ is not based on color appearance and generally is not used for creating colors for user interfaces.

XYZ's "Y" value, known as relative luminance, is used in WCAG 2.0 contrast calculations.

Sources:

  1. Mark D. Fairchild (2013). Color Appearance Models. 3rd edition. John Wiley & Sons, Ltd. Pages 70-74, 79
  2. Janos Schanda (2007). Colorimetry: understanding the CIE system. John Wiley & Sons, Inc. Pages 29-35
  3. R.W.G. Hunt (2004). The Reproduction of Colour. John Wiley & Sons, Inc. Pages 101-103
  4. R.W.G. Hunt, M.R. Pointer (2011). Measuring Colour. John Wiley & Sons, Inc. Pages 235-236
  5. Relative luminance. Wikipedia. https://en.wikipedia.org/wiki/Relative_luminance