Olo: The Impossible Color That Could Rewire Human Vision

In April 2025, a team at UC Berkeley achieved something previously thought impossible: they made a handful of people see a color that doesn't exist in nature. Named 'olo' after its LMS color space coordinates (0,1,0) in leet speak, this imaginary color is produced by activating only the M cone cells in the retina, bypassing the overlapping sensitivities of S and L cones that normally prevent such a pure stimulus.

The technique is as audacious as it sounds. The researchers mapped individual cone cells on the retina, then used lasers to deliver precise light doses targeting only M cones. The result: a blue-green of unprecedented saturation, described by co-author Ren Ng as 'more saturated than any color you can see in the real world.' The closest sRGB approximation is #00FFCC, but that's just a pale shadow of the real thing.

Why This Matters for Engineers

This isn't just a parlor trick. The Berkeley team is exploring whether this technology can be adapted for color blindness correction, potentially giving individuals with deficient cone cells a workaround. More ambitiously, Ng suggests it could lead to tetrachromacy—the ability to perceive a fourth primary color, expanding human vision beyond the current trichromatic limit.

For those of us who work with color spaces, displays, and imaging pipelines, this raises fascinating questions. If we can now generate stimuli that activate individual cone types, what does that mean for color calibration, HDR, and even AR/VR displays? The current sRGB and P3 gamuts are defined by the limits of human vision—but those limits just got a lot more interesting.

Skepticism and Open Questions

Not everyone is convinced. Professor John Barbur from City St George's, University of London, argues that calling olo a 'new' color is 'open to argument.' The technique is a significant technical achievement, but whether it truly creates a novel color or just a more intense version of an existing one is still debated.

Regardless, the implications are clear: our understanding of color perception is far from complete, and the tools to push its boundaries are just emerging.