Colours and computers

Who’s involved?

• CIE: International Commission on Illumination

Light

• CIE defines a set of standard illuminants, e.g. D65
• Short wavelengths are blue, medium green, long red.

Human perception

There seems to be a lot to do with how humans perceive colours. Things like which colours we can and can’t see, how we see some colours better than others.

• Colorimetry is the science of quantifying human colour perception.
• The CIE 1931 colour spaces are quantitative links between electromagnetic radiation and human colour perception. They’re the result of experimentation on humans.
• In normal light, human vision comes from the cone cells in the eyes. There are 3 kinds, each with their own peaks of spectral sensitivity (in the blue, green, and red regions).
• The CIE XYZ colour space can represent all colours that are visible to a human with average eyesight.
• Chromaticity is a specification of the quantity of a colour regardless of its luminance.
  • it consists of two independent parameters: hue and colourfulness (also known as saturation, chroma etc)
  • I believe that all of those 2D colour space plots that you see are CIE 1931 xy chromaticity diagrams.