"How much time did it take to make this image?" asks Theodore Gray, co-founder of app developer Touch Press, gesturing to the multi-coloured pattern of tiny lines shining from the iPad that sits between us. "The answer is, at this resolution, about eight hours per pixel."

Given that this iPad's Retina display measures 2,048 x 1,536 pixels, that means it would take one person more than two-and-a-half thousand years to create the picture in question.

The image is the 'colour map' from Disney Animated, the latest Touch Press iPad app, which is released today. The London-based company is known for obsessively detailed titles such as The Elements, The Solar System and Barefoot World Atlas. Its team has dangled priceless musical instruments from the ceiling to photograph them for The Orchestra app and shot 154 high-resolution videos of top actors reading Shakespeare for The Sonnets, but even they haven't spent two millennia making a graphic.