A non-spectral colour is a colour that is not present in the visible spectrum and cannot be produced by a single wavelength or narrow band of wavelengths of light.
- While spectral colours are evoked by a single wavelength of light in the visible spectrum, non-spectral colours are produced by a combination of spectral colours from different parts of the spectrum.
- Colours evoked by a single wavelength of light are often described as being produced by monochromatic light.
- Magenta, pink, cyan and brown are examples of non-spectral colours produced by combining different wavelengths of light:
- Blue and red = magenta
- Red and purple = pink
- Blue and green = cyan
- Red, yellow and blue = brown
- When we look around us, the colours of things we see rarely include pure spectral colours but are more likely composed of narrow bands of contiguous wavelengths.
- Since both the RGB and CMY colour models mix primary colours from different parts of the visible spectrum, digital screens and digital printers produce non-spectral colours.
- The RGB colour model generates a complete range of colours on TVs, computers and phones by blending the primary colours (red, green and blue) in varying proportions.
- The CMY colour model produces a full spectrum of colours by blending the primary colours of cyan, magenta, and yellow in varying proportions.
Related diagrams
Each diagram below can be viewed on its own page with a full explanation.
