Colour blindness, or more accurately, colour vision deficiency, is not considered to be a disability in the UK, but colour blind people do face many obstacles in daily life, using technology and gaming that most people with normal colour vision never even consider. There are different types and degrees of colour blindness and although following some of the guidelines below makes it easier for people with colour deficiency to distinguish different colour, there is one rule that fixes all colour blind issues for all those affected:
The Golden Rule: Never use colour as the only indicator
Colour vision deficiency has a simple design solution – don’t use colour as the only indicator for anything. It does not mean that you cannot use colour as an indicator at all. The Logitech G700 for example uses three red, orange and green indicators. A fully charged battery displays three solid green lights, low charge is one flashing red light and whilst it is charging green lights are cascading until it is fully charged. The LEDs could all be white and still users would have no trouble differentiating between fully charged, charging and low on charge.
Colour is an extraordinarily useful tool to convey information very quickly and it is possible to make colour as a cue more accessible for people with colour vision deficiency. We would not recommend using these instead of providing an additional differentiating element, but definitely try to implement as additional steps.
Use brighter simpler colours
Many people with colour deficiencies can still differentiate between brighter colours and only have trouble with subtle shades. Use bright colours and stay away from subtler shades.
High contrast background and foreground
People with different colour deficiencies may see some colours as lighter or darker than the norm and as a result, the foreground blends into the background. Use high contrast with neutral colours like black and white when shading the background. This is a great article on how to calculate colour contrast for legible text.
Offer a choice of colour schemes
Very few people are completely colour blind and if you offer a choice of colour schemes, players can select the option that works for them. When selecting your colours, keep in mind that red-green is the most common problem combination and that blue-red is a much better choice.
Limit the number of colours used
Some colour vision deficiencies only have a small number of easily recognizable colours and using a multitude of different colours can be very confusing. Choose a small number of colours and only apply them where they are most needed. Use the highest contrast in the most vital places, like differentiating between enemies and friendly players.
Are you colour-blind?
About one in people has some form and degree of colour blindness. There are a variety of colour blind tests available free on-line, but due to the lack of accuracy in PC monitor colour saturation, they are not best relied on. If you think that you may be colour blind, have your vision checked.