What Are Impossible Colors and How Can You See Them?

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Licensed cosmetologist and film critic Charlie explains what impossible colors are and why we can’t see them

Co-authored by Charlie and Eric McClure

Last Updated: July 21, 2026 Fact Checked

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• What are impossible colors?
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• Do they exist?
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• Types
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• How to See Them
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• Video

|Show more |Show less

The human eye is only capable of seeing a very narrow range of colors, but that doesn’t mean other colors don’t exist! Outside of the other spectrums of light (like ultraviolet, infrared, X-ray, etc.), there are still colors in our visible spectrum that the human eye simply cannot detect without some very radical tricks. Here, we partnered with a licensed cosmetologist and film critics to break down what impossible colors are, how they work, and what you can do to get a glimpse of these scientific oddities yourself.

Impossible Colors Explained

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Licensed cosmetologist and film critic Charlie says impossible colors are colors that humans cannot see. However, you can temporarily trick your eyes into perceiving something like them. They include shades like red-green and yellow-blue (two colors that can’t be seen at the same time).

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Section 1 of 4:

What are impossible colors?

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   Impossible colors are colors you can’t perceive under normal, natural circumstances. Your eyes have receptor cone cells that detect three different color channels: red/green, blue/yellow, and black/white. When your eye detects one of the color channels (say, red), the other side of the channel shuts down. This is why “red-green” is a type of impossible color! Your eyes cannot literally perceive impossible colors due to the limitations of how your eyes work.

   • As Charlie explains, “The brain processes colors through opposing color channels, like red versus green, so a color that is both red and green at the same time is considered ‘impossible.’ It's important to note that this is not a mix of two colors, but both colors at once.”
   • Take red and green, for example, says Charlie. “Our brains process these opposite colors as a single perceived tone, essentially by asking if there’s more red or green and then showing you that tone. While impossible colors would be two opposing colors at the same time. It’s hard to even imagine what that looks like.”
   • Some impossible colors only exist based on math. You can actually measure cone receptors in the human eye and calculate how the wavelength of light triggers some cells vs. others. There are wavelengths in the visible light spectrum that exist on paper and do not trigger any cones.
   • There are tricks to see some impossible colors that we’ll cover in depth later, but “impossible color” doesn’t automatically mean “you cannot see it ever.” It just means you can’t perceive the color naturally.

   Meet the wikiHow Expert

   Charlie is a licensed cosmetologist and film critic, with over 13 years of cosmetology experience. She also has over 20 years of self-directed study in film, and her Instagram account, @TakingFilmTooSeriously, has over 34k followers.
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   Impossible colors are not the same as infrared or ultraviolet light. According to Charlie, some animals can see colors and ranges of light that humans cannot. This happens via infrared or ultraviolet light, but those are not “impossible colors” because they exist on a completely different spectrum of light. Impossible colors only exist in the context of the light spectrum that’s visible to humans.

   • Infrared and ultraviolet colors are not visible to the human eye. Other spectrums include radio waves, microwaves, X-rays, and gamma rays. Together with the visible light spectrum, these different wavelengths make up the electromagnetic spectrum.
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Section 2 of 4:

Do impossible colors actually exist?

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1. 
   Whether impossible colors really exist is up for debate. There are a few ways of thinking about this. For one, in a strange way, no color exists. Take an apple, for example. An apple might be red in bright light, but turn the lights off and suddenly it’s black. Color doesn’t really exist—it’s not an actual property with physical matter. It’s just our perception of light bouncing off of objects. So, do impossible colors exist?

   • Some impossible colors don’t “exist” in the sense that you cannot see them ever. There are visual tricks we’ll cover below that you can use to see an approximation of certain impossible colors, so if you take “exist” to mean “we can see it,” those definitely count! A lot of them aren’t possible to perceive under any natural condition, though.
   • That said, Charlie says that in her experience working with people, some can see a wider range of colors than others.

Section 3 of 4:

Types of Impossible Colors

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   Forbidden colors These are the colors your eye can’t perceive because of the mechanics of your eye’s cone cells. When you see blue, for example, the part of your eye that detects yellow is shut off (that’s how the blue is perceived), so you cannot see “blue-yellow,” for example. Instead, you can trick your eyes to see a version of these colors by exposing your eyes to different colors in a pattern.

   • Example: Blue-yellow, red-green
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   Chimerical colors Chimerical colors are impossible colors you can detect using visual tricks. These colors exist purely in your brain as visual effects that are created by exposing your eyes to certain colors for a certain amount of time. It’s sort of like those “floaties” you see when you look away from a screen or bright light. Chimerical colors are the result of something known as “cone fatigue,” which occurs when a color strains certain cones in your eyes and creates visual artifacts. By combining certain artifacts, you can make the colors temporarily visible.

   • Example: Stygian blue, self-luminous red, hyperbolic orange
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   Imaginary colors These are shades and colors that mathematically exist in our visible light spectrum, but we simply can’t detect them. Our eyes aren’t accurate enough, or they’re physically unequipped with the cones necessary to detect these shades and colors.

   • Example: Hyper-green
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   Fictional colors Fictional colors are impossible colors as imagined by works of fiction or art. There are a lot of pieces of media that cover people who can perceive different wavelengths, or colors that only exist in alternate realities. Some works, like The Giver or Pleasantville, even focus on impossible colors as thematic devices.

   • Example: Hooloovoo, a “superintelligent” shade of blue from The Hitchhiker’s Guide to the Galaxy
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Section 4 of 4:

How to See Impossible Colors

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   Red-green Red-green is probably the most popular of the forbidden colors because it’s the easiest to trick your eyes into seeing. The other notable forbidden color is blue-yellow, but white-black is technically another one.

   • How to see red-green:
     • Put the red and green squares roughly 4–6 inches (10–15 cm) from your face.
     • Cross your eyes and try to get the two white crosses to overlap.
     • You will be able to perceive red-green in the middle temporarily.
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   Stygian blue Stygian colors are chimerical colors that appear to be extremely dark and extremely saturated at the same time. Stygian blue is a popular chimerical color. The stygian colors can be seen for a moment by wearing out the cone cells in your eyes. Here’s how:

   • How to see stygian blue:
     • Zoom in to the fatigue template.
     • Hold your eyes 6 inches (15 cm) or so from the box.
     • Stare intensely at the x in the middle of the yellow circle.
     • After 45-60 seconds, quickly glance at the x in the second box.
     • You should see stygian blue in a circle around the x.
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   Self-luminous red Self-luminous colors are chimerical colors that are so bright that they appear to radiate light that doesn’t exist. They’re very hard for the human eye to perceive for any extended period of time, but self-luminous red is considered easier to see.

   • How to see self-luminous red:
     • Zoom in to the green circle in the top left.
     • Hold your face 6 inches (15 cm) from your face.
     • Stare at the x in the middle of the bright green circle.
     • After 45-60 seconds, move your eyes past the grey box and stare at the white box.
     • You should see the bright pink color radiating from the middle of the white x.
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   Hyperbolic orange A hyperbolic color is a type of chimerical color that is more vibrant than anything on the visible color spectrum due to its extreme saturation. Some hyperbolic colors are functionally impossible to see, but you can usually get a good sense for hyperbolic orange using the process below.

   • How to see hyperbolic orange:
     • Stare intensely at the x inside of the blue circle on the left.
     • After 45-60 seconds, shift your eyes to look at the orange x.
     • You should see hyperbolic orange inside of the orange box.
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   Olo Olo is an impossible imaginary color discovered by scientists at UC Berkeley. It’s a shade of blue-green that can only be perceived by completely shutting off all but one type of cone cell in your eyes. You can follow our quick guide to get a sense for what Olo kind of looks like.

   • How to see Olo:
     • Turn the brightness up as high as it can go on your screen and make the image as big as possible (if it covers the whole screen, perfect!).
     • Stare at the red square for 45-60 seconds.
     • Quickly swap to the cyan square.
     • You should be able to see an approximation of what Olo looks like.
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   Purple Okay, it’s not technically an impossible color because we perceive it naturally, but purple is actually very unique in the context of the human eye. That’s because purple is not a color on the visible light spectrum. Violet is, but not purple. Your eye perceives purple as an imagined shortcut when it encounters conflicting information from blue and red. See, blue and red are on the two extreme ends of the visible light spectrum, and your brain actually struggles really hard to understand those colors at the same time, so it just invents purple!

   • How to trick your brain into perceiving purple:
     • Zoom in on the red and blue dots.
     • Now, scroll up and down really fast using your finger or the scroll wheel.
     • Notice how when you move really fast, the image turns uniformly purple? Cool, right?!
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