Kevin Montgomery R.G.D.

Inverse and Complimentary Colours

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Here’s a post I never got around to finishing. Kind of surprising considering it’s a pretty simple concept.

Adobe Illustrator has a neat feature to automagically pick out inverse and complementary colours. Have you ever wondered how to do that in Photoshop or InDesign? It’s not that difficult. Here’s how I do it.

To get a complementary colour:

  • Convert your colour into the Lab space.
  • Invert the ‘a’ and ‘b’ values.

That is to say, if your is L: 61 a:-17 b:-46, the complementary colour is: L: 61 a:17 b:46

To invert the colour entirely, you only have to go one step further. Subtract L from 100, for example:

L: 61 a:-17 b:-46 becomes L: 39 a:17 b:46

That’s it! Happy colour-exploring.

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