Greyscale colour space


Martin McBride, 2021-04-28
Tags colour greyscale
Categories computer science colour

Any RGB colour that has equal amounts of red, green and blue, will display as a shade of grey, for example:

  • rgb(0%, 0%, 0%) is black.
  • rgb(30%, 30%, 30%) is dark grey.
  • rgb(100%, 100%, 100%) is white.

In the greyscale colours space, the colour is specified by a single value. The colour is displayed as if the red, green and blue values were all equal. You can think of greyscale as a subset of RGB that includes only the pure grey colours.

The greyscale colour space can only show shades of grey. It is useful for images that don't include any colour, for example:

  • Text only documents.
  • Charts and diagrams that don't use colour.
  • Scans of black and white photographic images.

This image

A greyscale image only stores 1 value per pixel (the grey level), whereas an RGB image store 3 values per pixel.

If you found this article useful, you might be interested in the book Computer Graphics in Python or other books by the same author.

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