New study overturns 100-year-old theory on how we perceive colour

12 Aug 2022

This visualization captures the 3D mathematical space used to map human colour perception. Image: Los Alamos National Laboratory)

Changes to our understanding of colour theory could boost scientific data visualisations, create more vibrant colour displays and recalibrate the textile and paint industries.

A mathematical error has been discovered in a 100-year-old theory used to describe how people distinguish colours.

Researchers looked at the 3D mathematical space developed by the Nobel Prize-winning physicist Erwin Schrödinger and others. Known as Riemannian geometry, this theory implies that the distance between two colours is the length of the shortest path that connects them.

The theory has been used by scientists and industry for more than 100 years to create precise mathematical models that plot red, green and blue colours in a 3D space. These are the colours registered most strongly by our eyes, which is why the RGB colour model is used for screen displays.

In the new study published in the online journal PNAS, researchers said that using Riemannian geometry overestimates the perception of large colour differences.

The study claims that the principle of diminishing returns applies to human colour perception. This means that our perception of differences in colour would be less than the sum of the small differences between two widely separated shades. The researchers from the Los Alamos National Laboratory said Riemannian geometry cannot take these diminishing returns into account.

“The assumed shape of colour space requires a paradigm shift,” said lead author Roxana Bujack. “Our research shows that the current mathematical model of how the eye perceives colour differences is incorrect.”

Modelling human colour perception enables the automation of image processing, computer graphics and visualisation tasks. The conclusion of this study has the potential to boost scientific data visualisations, create more vibrant colour displays and recalibrate the textile and paint industries.

Bujack said they didn’t expect these results and still have to work out the exact geometry of a “new colour space”.

“We might be able to think of it normally but with an added dampening or weighing function that pulls long distances in, making them shorter,” Bujack said. “But we can’t prove it yet.”

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Leigh Mc Gowran is a journalist with Silicon Republic