Colour – in terms of accessibility – is one of the areas I find hardest to understand; I can read a sentence like,

‘avoid using colors of similar lightness adjacent to one another, even if they differ in saturation or hue.’ (from

And be as confused after I’ve read it as I was before.

I guess that is because – not having done a course on colour theory – I’m thrown by the jargon. In this weeks tip, I will define the words hue, lightness and saturation, and, having figured out what they mean – try to understand the above tip. Bear in mind that with these definitions I am simplifying as much as I can.


This is the easy one – just substitute the word ‘colour’ for the word hue and you have the meaning.


How much light does the colour reflect: black doesn’t reflect much, white reflects lots. Colours thus appear light or dark; how light or dark they are – tells you their ‘lightness’.


The purity of the colour – saturated colours contain no white, grey, black or complementary colours.

Ok – so now I’ll put the tip from the Lighthouse website into words I understand:

Even when using different colours next to one another (e.g. text and a background colour), if they are similarly light or similarly dark there will still be accessibility issues for some users.

Phew – perhaps this ‘colour business’ is not as impenetrable as I thought.


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