https://www.science.org/doi/10.1126/sciadv.adu1052
We introduce a principle, Oz, for displaying color imagery: directly controlling the human eye’s photoreceptor activity via cell-by-cell light delivery. Theoretically, novel colors are possible through bypassing the constraints set by the cone spectral sensitivities and activating M cone cells exclusively. In practice, we confirm a partial expansion of colorspace toward that theoretical ideal. Attempting to activate M cones exclusively is shown to elicit a color beyond the natural human gamut, formally measured with color matching by human subjects. They describe the color as blue-green of unprecedented saturation. Further experiments show that subjects perceive Oz colors in image and video form. The prototype targets laser microdoses to thousands of spectrally classified cones under fixational eye motion. These results are proof-of-principle for programmable control over individual photoreceptors at population scale.
A completely NEW COLOR that no human has ever seen before!
This April, scientists achieved something that sounds almost impossible —
using an extremely precise laser system, they made five participants see a color that no human has ever seen before.
It wasn’t just any green — it was a hyper-saturated, electric green, more vivid than anything that exists in nature or on a screen.
But here’s the twist — color doesn’t actually exist in the world.
It’s a simulation created by our brain to interpret different wavelengths of light.
Our eyes evolved with three types of cone cells —
L-cones for long wavelengths (reds)
M-cones for medium wavelengths (greens)
S-cones for short wavelengths (blues)
Everything we see — sunsets, rainbows, even LED displays — is just our brain mixing the signals from these three sensors.
But there’s a catch.
These cones overlap in their sensitivity, meaning there’s no real light in nature that can trigger only the M-cones (the “green” ones) without slightly activating the others. That overlap is also why two completely different spectra can look like the same color — a phenomenon known as metamerism.
So here’s the big question:
What would happen if we could stimulate only the M-cones — perfectly, with zero cross talk? What color would we see?
That’s exactly what researchers tried. Using an adaptive-optics scanning laser system, they mapped and individually stimulated hundreds of cone cells in real time, targeting only the M-cones.
The result shocked even them:
Participants saw a completely new color, something beyond the boundaries of the human CIE color gamut — a hue that no physical light or RGB display can ever reproduce. They called it “OLO.”
It’s not “greener green” or “bluer blue.”
It’s something else — a glimpse beyond the limits of human perception.
But what really struck me wasn’t just the discovery of a new color.
It’s what it says about us — about how our brains construct reality.
Color doesn’t actually exist “out there.”
It exists in here — in the brain.