Beyond the visible spectrum? Scientific discovery reveals an 'impossible color'
Researchers from UC Berkeley and the University of Washington have developed a new technique that allows people to perceive a color never seen before, Kazinform News Agency reports.
Published in Science Advances, the study introduces a display method called Oz, which uses a laser-based system to directly stimulate individual photoreceptor cells in the retina.
The Oz system targets the L (long), M (medium), and S (short) wavelength-sensitive cones in the retina by using light pulses to scan the retina. The technique creates a visual state that is impossible to replicate with natural light by detecting eye movement and limiting stimulus to M cones.
“Theoretically, Oz expands the natural human color gamut to any (L, M, and S) color coordinate. In practice, we achieve a partial expansion of colorspace toward this theoretical maximum,” the researchers explain.
“We introduce a new principle for displaying color, which we call Oz: optically stimulating individual photoreceptor cells on the retina at population scale to directly control their activation levels,” the paper states. “As proof of principle, we perform human subject experiments on a prototype Oz system that stimulates thousands of retinal cone cells.”
Using this method, researchers identified a new color, named olo, which falls outside the range of natural human vision and can be seen only when M cones are activated. The team shared an image that suggests that olo resembles greenish-blue or turquoise, but it is emphasized that the true hue can only be seen through laser stimulation of the retina.
The study stands out for producing colors beyond the natural spectrum. “The Oz principle of color reproduction introduced in this paper is fundamentally different (from the other color reproduction technology),” the researchers note.
“Unlike conventional metamerism that requires at least three light primaries, we showed that spatial metamerism can produce a range of colors from a single monochromatic light.” They add, “Spatial metamerism enables fundamentally new colors, such as olo, that cannot be produced by conventional metamerism.”
Scientists believe the Oz system could help explore how the brain interprets visual information and offer insights into conditions like color blindness and degenerative eye diseases such as retinitis pigmentosa.
