Before the picture of the blue and brown dress became the biggest Internet sensation since the day before when two llamas were filmed running from police, most people assumed that colour blindness was a fairly rare condition. It appears that is not the case. Rather than being a merely entertaining diversion like the llama video, the blue dress picture has actually served a great public service in uncovering what is actually an epidemic of colour blindness in society. Thanks to the dress, we now know that well over half of the population may suffer from some form of colour blindness.
It turns out about half of the population look at the blue and brown dress and see a white and gold dress, while others see a black and blue dress. The disagreement about the colour of the dress’ trim isn’t really that big a disagreement at all. The actual trim is black, but because of the contrast in the photo it is lightened, so reasonable people can disagree on whether it is gold, brown, or a faded black colour. The most interesting and enlightening disagreement pertains to the base colour, which is blue.
Shades of brown and gold can easily be confused and are often a matter of subjective judgement, as all colours are on a spectrum. Few blues are totally blue; there are a million slightly different shades of the colour and there is a shade that is exactly half way between purple and blue. White, however, is not on a spectrum with other colours; it is essentially the absence of colour. There is no such thing as a light white, a dark white, or a teal white; there is just white.
It isn’t just that colour blindness may be far more widespread than previously thought, it is that it may be taking on different forms than previously recognized, which may explain why this epidemic has gone unnoticed for so long. Generally colour blind people have trouble differentiating between colours like green and red when they are mixed together. What has been revealed is that there is a sizeable chunk of the population that cannot detect the presence of a particular colour at all. This seemingly superfluous viral picture may have unlocked an important medical issue.