Researchers reveal filters that trick our eyes into seeing 'invisible' colors

There are colors all around us that we cannot see – but a new pair of glasses could soon change that.

While human color vision relies on three types of photoreceptor cone cells, the specs essentially trick the eyes into having a fourth, allowing a person to see distinct hues that would otherwise appear identical.

The design opens the door to a slew of new ‘meta-colors,’ revealing a much wider array of blues, violets, and purples, and the researchers say it could one day be taken even further to double our number of effective cone types.

Typical human color vision is trichromatic, using three types of cone cells to process blue, green, and red wavelengths.

But, other animals are equipped with more complex visual systems that can process additional wavelengths.

Goldfish, zebrafish, some species of birds, and foraging insects are known to be tetrachromats, meaning they have four types of photoreceptor cells.

This extends their range of vision into the ultraviolet wavelength.

There are even some mammals with the capability, including reindeer.

It’s thought that there may even be some animals that are ‘pentachromats,’ as some birds and butterflies have five or more kinds of color receptors.

And, mantis shrimp are known to have up to 16 types of color receptive cones.

Typical human color vision is trichromatic, using three types of cone cells to process blue, green, and red wavelengths.

But, this creates some limitations in the form of ‘metamers’ – colors that appear identical but actually have a different spectral composition.

To break the ‘inherent redundancy’ of human color vision, researchers from the University of Wisconsin-Madison developed a device that uses two distinct transmission filters, with one for each eye, according to the study.

Doing this split the response of the short-wavelength cone, effectively inducing ‘tetrachromacy,’ or the presence of four distinct cone types.

With the glasses on, a wearer can recognize the difference between the metamers, allowing them to see new colors that were previously undetected.

‘They look exactly the same and you look through the spectacles and, holy crap, they’re two different things,’ physicist Mikhail Kats told New Scientist.

Other animals, such as goldfish, are equipped with more complex visual systems that can process additional wavelengths.

And, these glasses could bring humans up to par.

‘This design allows users to differentiate between various blue, purple, and violet metamers, without apparent adverse effects,’ the authors explain.

‘We posit that the extra spectral information can be understood as creating a set of new ‘meta-colors,’ distinguishable from colors perceived without the filters.

 ‘The methods introduced here can, in principle, be used to split any cone or combination of cones, resulting in a visual system with up to six effective cone types.’

The system could allow humans to spot the differences between objects based on emission, reflection, and transmission spectra – and so far, they haven’t seen any adverse effects.

Ultimately, the researchers say, the ability to enhance humans’ color vision could make for much more precise camouflage detection methods, and anti-counterfeiting in art and data visualization.

Follow NEWS.am Medicine on Facebook and Twitter