Many years ago, while having lunch with some friends in Queensland, I admired a distant poinciana tree whose masses of red flowers stood out vibrantly against a background of rich green foliage.
My companions were unimpressed. 'Is it flowering?' asked one of them indifferently.
'I can't tell either,' said another.
Not one, but two of my lunch mates - both male scientists - were red/green colour blind. During the conversation that followed, words failed us and I became more and more puzzled as to what my friends were actually seeing. Did the tree look all red to them? All green? Was it some unnamed colour that I myself couldn't perceive?
During the 20-odd years that I worked in science, I found that this form of vision was quite common among my colleagues. (In fact, about 8% of men of Northern European extraction are colour blind). I learned not to make slides or maps that used red or green to distinguish different types of data. Instead shapes, tones, and patterns were needed to ensure that everyone in the audience could quickly understand the information.
Thanks to the internet, today I have a slightly better idea of what my friends were seeing. Here's a picture I posted a little while ago, which used a carefully worked out pink and green colour scheme:
And here's approximately what it looks like, to a person with red-green colour blindness:
Clearly, it could have looked better if I'd aimed for greater tonal contrast, to help counteract the merging of the reds and the greens.
The reason I've been pondering all this is that I've been asked to illustrate a very interesting and challenging picture book text, 'Fire Engine Green', by Castlemaine writer Toni Pellas. Toni carries the gene for red/green colour blindness, and has many family members who can't distinguish these colours. Her convivial and engaging text is a blend of fiction and non-fiction, explaining colour blindness to kinder and early primary school children. Toni plans to run a Pozible crowdfunding campaign in a few months' time to generate interest and funds for the book. During the lead-up to the campaign, I have time to enjoy doing research and playing with ideas for the illustrations. I think it will call for appealing characters and drawings with strong tonal contrast, shapes, patterns, textures and just a few splashes of colour where necessary.
During my research I found some great websites. Here's a fun online colour challenge, where you can arrange 100 squares to test your own level of colour vision acuity. I have done the test on three different days - once with a perfect score, once with errors at the blue-green end, and once with errors at the pink-orange end. It seems that anyone's colour vision acuity can vary from day to day!
See a simulation of how things look to people with different types of colour vision:
Check how your paintings look to people with different forms of colour vision: http://www.color-blindness.com/coblis-color-blindness-simulator. The results are sobering!