Colour and contrast
Why is colour and contrast important?
Considering colour and contrast isn't just about people being blind or having vision issues, it is important to everyone for many reasons:
- there are approximately 3 million colour blind people in Britain approximately 4.5% of our population
- colours on a screen can seem less vibrant in the sunshine and may not be readable if there is too little contrast between foreground and background
- colours, contrast, resolution and size can vary between screen and projectors
- tired eyes have to work harder when colour contrast is poor, this can lead to eye-strain and headaches
- the amount of light that reaches the back of the eye reduces as a natural part of ageing
Why do it?
People who are blind, have low vision, or are colour-blind might miss out on the meaning conveyed by colours alone so use other distinguishing factors too.
If your document has a high level of contrast between text and background, more people can see and use the content.
How to do it
You need to ensure that colour is not the only means of conveying information
For example, you may have a graph using two different colours for positive results and negative information. However some vision conditions mean people may not be able to decifer the two colours and therefore may not be able to distinguish or interpret the information using colour alone. In this example you should also label the content.
Use sufficient contrast for text and background colours
The Microsoft Office Accessibility Checker (opens in a new window) will list any accessibility issues in your document, including insufficient colour contrast.
You can also manually look for text in your document that’s hard to read or to distinguish from the background.
- Use accessible text colour (opens in a new window)
- Use accessible text format (opens in a new window)
Tools for checking colour and contrast
- Google Chrome NoCoffee Vision Simulator (opens in a new window)
- Colour Contrast Analyser (opens in a new window)
Video: the importance of colour contrast
This video has captions, these can be found by clicking on cc in the YouTube player functions