Most Humans Can See 10 Million Colors. Cal Scientists Found One More.

What if you could create a color, one that no one had ever seen before? That’s what a team of UC Berkeley scientists set out to do, and in the process they found a new green — one so intense a camera could not capture it and a printer could not replicate it. How they did it and how their discovery may change what we know about color science and how the eye works are the subjects of a New Yorker article by Rivka Galchen, “What Would It Mean to See a New Color?” We talk to Austin Roorda and Ren Ng, the scientists behind the work, and Galchen.

Guests:

• Rivka Galchen, Contributor, The New Yorker Magazine – She wrote the article “What Would It Mean to See A New Color?”
• Ren Ng, professor, University of California Berkeley Electrical Engineering and Computer Sciences
• Austin Roorda, professor, Optometry and Vision Science University of Waterloo, runs the Roorda Lab at UC Berkeley

This is a computer-generated transcript. While our team has reviewed it, there may be errors.

Alexis Madrigal: Welcome to Forum. I’m Alexis Madrigal. Maybe you’ve gotten into a debate about the dress, a meme from years ago on the internet, or whether a tennis ball is green or yellow, or whether something is red or pink. And in these debates, our own experiences feel undeniable. Of course a tennis ball is green. That’s because the colors we each see feel like reality, but they’re actually something more complex.

They do have a basic basis in physics — wavelengths of light and all that, you know — but the way they’re rendered to your conscious mind relies on our visual perception system, and that turns out to be much more variable between people than is commonly appreciated, as the research we’re going to hear about today will highlight.

So let’s get to it. This morning, we’re joined by Rivka Galchen, staff writer at The New Yorker. Her piece in The New Yorker is titled “What Would It Mean to See a New Color?” Welcome.

Rivka Galchen: Thanks for having me.

Alexis Madrigal: We’ve also got Austin Roorda, who’s a professor of optometry and vision science at the University of Waterloo, Canada. He ran the Roorda Lab at Berkeley. Welcome.

Austin Roorda: Thank you. Happy to be here.

Alexis Madrigal: And we’ve got Ren Ng, who is an associate professor in electrical engineering and computer science at UC Berkeley. Welcome, Ren.

Ren Ng: Tickled pink to be here.

Alexis Madrigal: Let’s just get a little bit about your relationship to color here. Rivka, um… Do you actually have a favorite color?

Rivka Galchen: Oh, it’s obviously green.

Alexis Madrigal: Ah, but what kind of green?

Rivka Galchen: Yeah, sort of an emerald, not grass, a very synthetic kind of green. Who knows why? Who knows?

Alexis Madrigal: Yeah, yeah, like Lego green. Is that what we’re talking about?

Rivka Galchen: Yeah, a sort of, you know, new T-shirt, 1984 green. Perfect.

Alexis Madrigal: Uh, Austin, how about you?

Austin Roorda: Well, I have to say, although you don’t believe me, one of the persons that saw it — that’s my new favorite color.

Alexis Madrigal: Okay, we’ll come back to that in a second. And Ren, what about you? Before you saw OLO, this new color, what would you say?

Ren Ng: As my children quiz me all the time and know, it is dark blue, ultramarine, navy, but my wife’s is teal.

Alexis Madrigal: Aha. And that actually does relate to this color, OLO. Let’s talk about how this research into this new color got started. Ren, I mean, talk to us a little bit about where this all came from, this idea of being able to get a new perception of color.

Ren Ng: For me, it started when I was starting to give lectures at UC Berkeley in computer graphics about color. We have a week on color. And I’d inherited slides from lots of other professors. This is what we do when we start to teach a new course.

And for me, color in my mind was much more simplistic. Kind of, you know, from the engineering perspective, kind of like RGB. You know, the color is in our displays. But there was a whole week on it. And this really befuddled me at first, but I tried to sort of get up to speed on why there was all this depth.

And one of the things I saw in there was a picture that Austin had made that showed a picture of the retina and all the individual cells on it, and also which color type, spectral type, of those cells they were. And in trying to think about that and to be able to lecture on that carefully, I wanted to understand that better.

So I looked into Austin’s work, and this is where this opportunity to show a new color opened up.

Alexis Madrigal: Austin, why don’t we use that as an opportunity to talk about how our eye perceives color? Could you give us like a little primer on that?

Austin Roorda: Sure. Okay, well, the human retina is comprised of cones and rods, and the rods are exquisitely sensitive to dim light, and the cones are what we use for our daylight vision.

And the cones come in, I’d always say, three flavors, sensitive to short, middle and long wavelengths, and that’s why we call them the S, M and L cones. But you might consider them as blue, green and red for a better understanding.

And so images that the optics of our eyes cast onto our retina are received by these three cones. There’s some processing of those signals that happens in the retina, but ultimately signals from the retinas go to the brain through the optic nerve.

Comparing the amount of L cone excitation versus M cone green excitation versus blue S cone excitation, we can sort of differentiate different spectra in the world. And the brain’s big job is to make sense of those sensory inputs that are getting sent to it from the eyeball and generate a percept of the color.

Alexis Madrigal: And also, you know, our brains are also expecting certain things too, right? Like when we look at something where we have a sense of what should be there in a lot of cases, right? Kind of tuned by just having been alive in the world.

Austin Roorda: Oh, exactly. And really all of our perception is what you might call an inference — our best guess of what’s in the world based on the sensory inputs that come in.

And we learn to do that as we develop, right? We refine our ability to perceive the world based on the brain learning those sensory inputs that come in. And so, in the end, it becomes almost immediate. We’re so good at it that as soon as the brain sees a sensory input that suggests that that shirt is red, we immediately generate a perception in our mind of a red shirt.

Alexis Madrigal: Well, and Ren, this is why this research got you, et cetera, because you’re like, well, what if you could generate a color that has not been seen before, right? Like, how would the brain process such a thing?

Ren Ng: That’s right. And the basis for it is something that’s well known to vision scientists, which is these three flavors of cone cells, the color-receptive cells in the retina, as Austin described.

The middle one, the M cone cell — they all respond to a broad set of wavelengths. They just have different peaks in wavelength that Austin described. But the middle one, the M cone cell, never gets stimulated by itself in normal vision.

And the reason for it is that its sensitivity overlap as a function of wavelength overlaps completely with the other two. So if there’s any wavelength of light that’s coming to your eye and is stimulating M cone cells, it will for sure also be stimulating the L and/or the S cone cells that are around it.

Austin’s research for his career has developed into a technology for seeing the eye, these cone cells individually on the retina in a living person’s eye, and to track its constant motion, and also to be able to stimulate individual cells.

And this, of course, presents a new possibility. If you can go onto the retinas with a laser — you know, tracking a scanning laser — and then stimulate individual cells very quickly, one can imagine a new thing which is simple to say: Now let’s just only visit the M cone cells and only stimulate them. And that never happens in the normal viewing of the world. What would that color look like?

Alexis Madrigal: Such a cool idea. We’re talking about the discovery of a new color or kind of a new experience of color. It’s called OLO, and we’re gonna get to what it is like in a little bit, what it might actually look like.

We are joined by Ren Ng, an associate professor in electrical engineering and computer science at UC Berkeley. We’ve got Austin Roorda, professor of optometry and vision science at the University of Waterloo, Canada. And we’ve got Rivka Galchen, who is a staff writer with The New Yorker. And, of course, she wrote about this new color, OLO.

We’d love to hear from you. Have you ever argued with someone about what color something was? You can give us a call, 866-733-6786, [email protected].