Like many people, I am colourblind.

Fortunately I am only ‘mildly’ red-green colourblind and it doesn’t have a huge detrimental effect on my life.

Firstly, to dispel a couple of misconceptions:

1. I can still see colour. ‘blindness’ here would be better called ‘deficiency’ or ‘desensitivity’. I am simply less sensitive to reds/greens than the ‘normal’ eye. Whilst I can discriminate between blues/yellows, it is harder to distinguish some reds from some greens.
2. Colour blindness is not the swapping of colours. I don’t accidentally call red and green the wrong things – I just can’t tell what a colour is in some cases.
3. I have no problem with traffic lights.
4. Colour blindness does not mean poor eyesight. My cornea, lens, etc work fine, thank-you-very-much.

Approximately 8% of men and 0.5% of women are colourblind to various extents. There is a wide range of types, and severities, of colourblindness. For more information, there are a number of websites with helpful descriptions – This, for example…

There’s even a nature paper about colour blindness awareness…

The standard tests for colour-blindness are the well-recognised Ishihara colour tests. Lets do a few (just for fun)…

An example Ishihara Colour Test. Most people can see the ’12’ in the image. Image: Wikipedia

Another Colour Test. You might be able to see a ‘6’ in the image (I can’t…). Image: Wikipedia

Another Colour Test. You should see nothing in this image. I see a ‘2’. Image: Wikipedia

The last one. You should see a ’42’. I can just about see a nondescript blur that might be a ‘4’ on the left hand side. Image: Wikipedia

To give an idea of what it’s like, this page gives a very good example. For a theatre booking system, they indicate the seats that offer a restricted view of the stage –

Restricted view seats are clearly indicated – or are they? Image: www.digitalartsonline.co.uk

Whilst most people will be able to tell where the best seats are, for those with colour blindness it might not be so easy. The image below shows the same image from the point of view of someone with colour blindness – can you still be sure of which seat is which?

Still clear? Image: www.digitalartsonline.co.uk

Mostly, being colourblind doesn’t affect my life (when I’m not at the theatre). However, there is one area of my life where being colourblind is *really* annoying: presentations (and picking ties to match shirts, but I’ve got that figured out now).

So here’s the Nick-approved guide to making colour-blind friendly presentations.

1. Choose a colour scheme that is colour-blind friendly – these are readily available online. This is mainly for graphs. Just generally avoid pale green-pale red mixtures. Purples and pinks can also be pretty confusing.
2. Along with the above, high contrast colour schemes can be very hard to see. For instance, a presentation with a white background can make it difficult to see coloured things on the slide, as everything is drowned out by the white background – especially yellow/green text. It is also very tiring to the eye. Try dark-coloured fonts on a light-coloured background.
3. In graphs, don’t just use colours to match lines to the legend – matching colours from lines to the colours on the legend is hard – use shapes as well, or label the lines. An example.
4. If 3. is impossible, make the lines on graphs a decent thickness – small areas of colour are harder to determine.
5. When referring to slide, try not to refer to ‘the red box’. Refer instead to ‘the rounded red box in the top-right of the screen’.
6. Please don’t use red laser pointers – these are evil [citation needed]. The red light is not easily distinguishable on bright screens (or if it’s zipping around the screen). Use a green laser pointer instead. Not only are green laser pointers generally more powerful, and therefore brighter, but they are also easier to see. Why?

For a fairly comprehensive guide of how to make colour-friendly presentations, look at this page. And for checking how things might look, there are many colour-blind simulators for both images and webpages.

I hope this helps to create colour-friendly presentations.