How Pixar Uses Hyper-Colors to Hack Your Brain | WIRED
Lighting a computer-rendered Pixar movie isn’t like lighting a film with real actors and real sets. The software Pixar uses creates virtual sets and virtual illumination, just 1s and 0s, constrained only by the physics they’re programmed with. Lights, pixels, action. Real-world cameras and lenses have chromatic aberration, sensitivities or insensitivities to specific wavelengths of light, and ultimately limits to the colors they can sense and convey—their gamut. But at Pixar the virtual cameras can see an infinitude of light and color. The only real limit is the screen that will display the final product. And it probably won’t surprise you to hear that the Pixarians are pushing those limits too.
Using color to express emotion is a hallmark of life. (Humans aren’t even the only animals to send signals with a bit of sexy red or dangerous green.) But the mechanical production of color has defined and changed human cultures since before recorded history. The technology for making colored things and the science of how those colors work in the world and in our minds changes and evolves, transforming culture along with it. Right now, that technology is evolving again.
First of all, you have to forget the dorm-room philosophizing about whether you see the same red that I do even though we both call it “red,” man. If we both agree—and let’s agree to agree—that “red” is light with a wavelength of somewhere above 620 nanometers, well, waves of what, exactly? (It’s fluctuations in electrical and magnetic fields, as if that helps.) Or we could agree that “red” light is made of subatomic particles called photons, the irreducible quanta of energy—1.8 electron volts, to be more or less exact.
Go ahead and map those electron volts and nanometers for red, plus the ones for all the other colors you can name, into a straight line, or even wrap them into a circle as the physicist Isaac Newton did. You still won’t be capturing everything that comes together to mean a color. The real map needs more dimensions than that. It needs the amount of color, from pastel to saturated. It needs the amount of light you’re talking about. That’s “luminance,” or sometimes “intensity.” Color that’s made of light is different from color that’s light bouncing off a surface, changed not only by how that light reflects or refracts but also by whether the surface is colored itself, maybe by a pigment. Map all those values together, usually in three dimensions, and try to match the objective numbers to the vagaries of the way human color vision works—we see yellow as brighter than other colors, even if the actual brightness is equal, and that’s just the beginning of the headaches—and you have what’s called a color space.
Control the lighting, control the colors, control the feelings. That’s filmmaking. As of this writing, Pixar’s last 23 movies—going back to 1995’s Toy Story—have made a combined $14 billion globally, and that’s not even adjusting for inflation. Kids like them; adults like them. Even in a locked-down, movie-theater-free world, the latest Pixar movie, Soul, grossed $117 million worldwide.
But I’ll tell you a secret: When it comes to wringing emotion from color, Pixar cheats.
Newton broke whitish sunlight into a rainbow’s worth of colors and chose to draw the borders at seven: red, orange, yellow, green, blue, indigo, and violet. He called that a spectrum, but of course that categorization leaves out a lot—the “extraspectral” colors like pink or purple or, yes, brown. (Brown is just dark yellow. Shh.)
If you’re reading this on a screen instead of on paper, you’re seeing a concatenation of light generated by red, green, and blue pixels—a whole other set of primaries, not coincidentally at similar wavelengths to those the color receptors in your eyes are tuned to. A little more or a little less of each, and just as with CMYK pigments (and white light or white paper), you can make just about every color that the human eye can discern. Point is, the colors we see aren’t actually mixed from a list of available ones, like buying from a paint store. It’s a continuum of light and reflection, interpolated by the biological sensors of our eyes and the not-totally-understood think-meat just behind them.
The colors a projection system can reproduce are bounded by a triangle-shaped color space—red, green, and blue at the corners, and everything else a mixture of those inside the lines. But that color triangle is invariably smaller than the possible colors of the universe, or even those that the human eye and mind can distinguish. Which leaves a little wiggle room for Pixar. “The specific hues at the red, green, and blue corners of that triangle are not really what you’d experience under, say, ultraviolet illumination,” Glynn says. “We said, ‘Hey, what would happen if we tickled all the portions outside a traditional cinema gamut?’”
This quirk of human color vision has vexed scientists since before anyone knew about the color photoreceptors in the eye. Color-thinkers in the 19th century recognized that the same colors—or rather, objects of the same color—might look different depending on context, on what colors they were adjacent to.
They also recognized the obverse—different spectra can appear the same in different contexts. This was one of the tricks that the color-seeing brain could play. Varying levels of brightness change the colors people see. Look away from a bright light, like a candle, and the afterimage you’ll see is the color of that light’s complement on a color wheel. In all those cases the brain seems to be generating colors that aren’t there.
Now, Glynn says, it might be possible to take control of those illusory effects. Blast the middle-wavelength greenish receptor in the eye with light at its peak sensitivity and “you can actually heighten the sensitivity or perceived sensitivity to other colors in complement to that.”