An Unknowable Color

The human eye can see roughly 10 million colors, but scientists recently found that there is actually more than the eye can see. 

In a new study, researchers at the University of California, Berkeley, manipulated human sight via lasers to discover “olo,” an impossibly saturated blue-green hue that doesn’t exist in nature and can’t be recreated on a screen. 

“It was like a profoundly saturated teal … the most saturated natural color was just pale by comparison,” Austin Roorda, a professor of optometry and co-author of the paper, said in a statement. 

Roordra and his colleagues explained that human color vision is mainly based on three cone cell types: S, M, and L cones, which pick up blue, green, and red, respectively, when they pick up wavelengths of light. 

But to find the new color, the team used a new laser-based technique called “Oz” – named after the Wizard of Oz. 

“We chose Oz … because it was like we were going on a journey to the land of Oz to see this brilliant color that we’d never seen before,” said James Carl Fong, another co-author of the study. 

The team developed Oz to stimulate individual photoreceptors in the eye using precise microbursts of laser light. They first mapped each subject’s retina, identifying the three types of cone cells – S, M, and L – that process different wavelengths of light. 

For their experiment, five participants – including the authors themselves – entered a darkened lab, sat at a table, and had their retinas blasted with lasers. 

Researchers mapped each volunteer’s retinal cone layout and stimulated only M cones, producing a color experience the brain had never processed before. 

They then tested their breakthrough using jittering and color-matching experiments, which confirmed that olo doesn’t match any known hue.  

“When I pinned olo up against other monochromatic light, I really had that ‘wow’ experience,” Roorda noted. 

While the findings update our repertoire of colors, scientists explained that the study opens new doors about understanding human vision, too. 

Co-author Ren Ng told Scientific American that Oz – while still in its infancy – can help develop innovative display screens that scan retinas and show perfect images and videos.  

Beyond novelty, the tool could also aid people with color blindness to experience all the hues of life in the future. 

“That’s going to be extremely hard to do, but I don’t think it’s out of the realm of possibility,” Ng said.