Years ago when I was art director for some magazine or other, a letter arrived from a subscriber who was frustrated with an article in the current issue. It seems that I had designed some info-graphics – a series of bar and pie charts – with colours he couldn’t distinguish between.
While it’s extremely rare to be totally colour-blind – a complete absence of any colour — there are many variations and varying degrees of colour vision deficiencies. One out of twelve men, and one out of two-hundred women suffer from one form or another, ninety-nine percent of whom have either red- or green-weakness.
An example: with normal colour vision one sees a set of traffic lights as red, amber, and green… whereas someone with deuteranopia would see amber, amber, and amber.
Some good examples of this severe form of colour blindness are located here.
The simplest solution, graphically-speaking, was to continue designing info-graphics with whatever colours I wanted, but to be sure they were well-labelled, so that all readers could understand what was being illustrated.
What I would really like to see is a filter in graphics and photo editing software that can “preview in dichromat” — much like this wonderful palette sampler.
Around the time I picked up this book, I had been watching a documentary film on cephalopods, which touched on the ability of some species to communicate through the use of chromatophores – pigment-bearing cells that change colour. Together, the book and the documentary inspired the illustration at the top of this post. I drew five different species of cephalopods and included the number five as a colour-blindness test on the surface of the octopus.
Here are a couple of more tests from Doctor Ishihara’s book: