The wizardry of Oz shows people colors beyond normal human perception

Amazing stuff!

"But it turns out that some patterns of activation are impossible—the wavelengths that activate green-sensing M cones completely overlap with those of blue S cones and red L cones, so it’s impossible to just see pure, true greens… or it was. Now, thanks to a new system called Oz, people can see totally new colors , and scientists can learn more about how perception works.

Oz uses teeny lasers to light up individual cone cells on the retina, directly controlling how much they are activated. Theoretically, Oz can show people “any (L, M, and S) color coordinate,” ... And in their study, they succeeded in showing five participants a new, highly saturated blue-green, a theoretical color the team dubbed “olo” because of its color space coordinates—0 activation of S and L, and full activation of M, or [0,1,0]. ..."

"Ground Summary

• The Discovery: ... researchers used a laser system called 'Oz' to create 'olo', a never-before-seen blue-green color, by selectively stimulating M cone cells in five participants' retinas. The breakthrough occurred yesterday at the University of California.
• Why It Matters: This breakthrough could revolutionize treatment for color blindness and expand human color perception. The technology may eventually simulate tetrachromat vision, potentially allowing humans to see 100 times more colors than currently possible.

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From the abstract:

"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."

ScienceAdviser

UC Berkeley Researchers Reveal 'Olo,' a Color Beyond Human Vision (original news release)

Novel color via stimulation of individual photoreceptors at population scale (open access)

By directly stimulating certain light-sensing cells (s, m, and l) in the retina, researchers can show people colors outside the natural range of perception—like “olo” (green circle).

Fig. 1. Overview of principle and prototype system.