The work resulted in a “principal odour map” – the olfactory equivalent of the colour palette you might use on a computer. “Anybody who’s looked at a map of colour in Photoshop knows intuitively what’s going on,” says Mainland, and just as the “colour space” in such a map helps us say that purple is closer to red than to green, the team’s odour map allowed them to locate scents in a kind of multi-dimensional “smell space”.

“RGB is three-dimensional, but you can depict it on a flat piece of paper,” [Alex] Wiltschko says. “There’s three channels of colour information in our eye, but there’s 350 channels of odour information in our nose.

— Read more in ‘Giving computers a sense of smell’: the quest to scientifically map odours at The Guardian.