Can you see bluish yellow or reddish green?

While at the airport on my way to Chicago last weekend I picked up the Feb issue of Scientific America. It’s always a good read and I was particularly intrigued by an article on impossible colors, colors that we are not supposed to see. Can you imagine a reddish green (greenish red) or yellowish blue (bluish yellow).

You can read about the theory here but cut to the chase and do these simple tests below to see the colors for yourself.

  1. Click on each of the graphics below, this will bring up a much larger image in a new browser.
  2. Hold a finger in front of your nose and focus intently on it. This will cross your eyes.
  3. Slowly remove your finger from view
  4. On your screen you will see three boxes. The middle box will show the impossible color, a bluish yellow or a reddish green. Make sure the crosses line up.

Can you see yellowish blue?

bluish yellow

Can you see reddish green ?

reddish green

It took me a while to master the visualization technique but it is a bit like doing the magic eye pictures. The key to seeing the colors is to hold the cross steady. They are pretty unstable and seem to flick in and out but they are definitely colors I have never seen before.

How about you, can you see them?

2010 © St Louis Web Designer

18 thoughts on “Can you see bluish yellow or reddish green?

  1. Actually, they're not new colors. Bluish yellow = green, and reddish green = yellow (or in your example, closer to orange), just as you'd expect.

    The only reason they look any different is because our eyes only do a moderate job of mixing the two colors, flickering back and forth between giving each eye (and therefore, color) dominance.

    You can produce a similar effect by interlacing (alternating lines) the two colors in Photoshop.

  2. Thanks for stopping by and trying this out Clay.

    I beg to differ on the colors though. When viewing the bluish yellow example I see a weird color that is definitely not green.

  3. Actually I think Clay is also wrong. Yellow and Blue, If our eyes did a better job of mixing would be white.

  4. This was a fascinating thought process. Initially I thought exactly what Clay is describing, and was curious about the lack of agreement.

    When I looked at this I didn't see blue and yellow making green, but the interlacing and flicking back and forth is precisely what I saw.

    I did some experiments in a graphic program:

    The 1st column the first color, 2nd an interlace (1 pixel of one followed by one pixel of another) of the 1st and 3rd columns. The 4th column is the color with 50% of the other overlayed (digitally mixing them).

    If your browser scales images automatically, you may not see the interlacing well without viewing full sized, but it is fascinating to watch the browser scale the interlacing down to the mixed colors in the 4th column.

    This turns out to be because it scales images poorly, but so does everything else apparently (

  5. I took the photos right in front of my eyes for a good 30 seconds. And then crossed my eyes when I pulled it back.
    I put together what looked to be a reddish cross in the (blue-yellow) with the other cross. (The different color crosses was from my eyes trying to adjust to the one color blasting my eye).
    I saw what looked to be a yellow with a blueish hue. If you took yellow and put a blue filter over it. And a different weird shade of green for the other.

  6. The colors seen in our selectively stabilized image experiments were more robust than the colors seen by superimposing monocular opponent colors. They were analogous to seeing purple, in which both the red and blue components could be identified, but neither described the perceived color. In seeing reddish-green and yellowish-blue, both components were identifiable, but the perception was one of simultaneously perceiving both components, not an additive or subtractive mixture of those components. That is, the colors seen were not brown, yellow, or green; but both red and green or yellow and blue in the same place at the same time.

  7. Reddish Green makes sense to my eyes. Reddish Green reminds me of apples not quite ripe yet, and that is something my brain can work with. Now, Yellowish Blue hurts my eyes, and it does not compute. The best I could do with Yellowish Blue is to have it sort of make green in my mind’s eye.

  8. Interestingly enough, I found that the longer I looked, the more the colors seemed to blend – reddish green became an odd shade of orange, and the yellowish blue became a muddy green. This may have been due as much to afterimages as to my brain managing to comprehend what it was seeing, however.

  9. Red and green eventually blended into a tan color for me
    Blue and yellow never fully mixed, I kept seeing a yellowish blue which was strange

  10. Not referring to the mixing of colors. But the mixing of light spectrum. Blue and yellow will make white, green and red…actually magenta make yellow.

  11. I was viewing this on my phone up close to my face and something interesting happened. When my phone light dimmed suddenly the colors flipped on the yellow and blue sides and a couple times I recreated it I got this weird color in my mind almost like a grayish color. I couldn’t get anything other than turquoise though when I did the experiment correctly. The red and green one I only got brown. I’m wondering if anyone has tried this using VR goggles and transmitting different colors to the opposite eyes.

  12. Wow I’m a few years late to the party, but when I did the green red color experiment, I found that with my eyes it would alternate back and forth between red on top of green and green on top of red making this strange combo of the two. Green on red made it look like a more bland green with red hues throughout, and red on green made an almost red orange color but with green underneath. And this was my eyes doing this, now with the blue yellow, the colors continuously swirled around and the cross in the middle almost gave a sort of glowing appearance. The white cross in the blue mixed with the white cross in the yellow and gave the cross a yellowish interior and a glowing blue edge. I find this experiment absolutely incredible as I’ve been thinking a lot about how the human mind and eyes perceive things and how there are so many things out of our reach. It feels like a leveling up system and being a human is like sub tier when it comes to extra perks like night vision or ultraviolet cones in hummingbirds eyes . That’s another incredible thing and the reason I was looking this up in the first place. It was said that birds can perceive colors like uv-red which isn’t really a “color” per say but more of a mix of red and uv which can only be seen under a black light usually. They can see up to I believe 4 extra colors that we can’t. Similarly humans have an extra color that is not technically in the spectrum and that is purple because you have r,o,y,g,b, indigo and violet, so it’s not really the color purple. This is because again purple has no visible light beam on the spectrum, but we can perceive it or at least we’re perceiving something that doesn’t technically exist. All of this came about because I’ve been researching a lot about N,N-Dimethyltryptamine or dmt, the spirit molecule. See I’ve been thinking a lot about how humans are only limited to their senses and they’re great for most things but there are many things humans could truly benefit from if we had these extra sensory devices, like having “night vision” for example . Dmt is found in your body and especially in your brain, it’s thought that dmt is released more when you are born, dream, and die. And is thought to be a highly needed compound in everyday existence. This all makes a lot of sense to me because when we dream most people have quite vivid dreams but are usually unable to remember most of them, this is most likely due to the fact that you are in a different state of mind, specifically if it is true that dmt is released when you sleep that could mean we are basically in the dmt realm but it’s way less intense and a little bit easier to understand. Most people that have tried dmt have said it is very difficult to explain what they are seeing because again you are in a different state of mind, same reason it’s weird to talk about how it feels to be high, it’s hard to describe it it’s not like dmt by any means but it does share the same characteristics as an altered mental state. But what I’m getting at with this is, if it is assumed that you visit this realm when on dmt and your brain releases dmt when you are dreaming, born, and death especially, maybe these beings or entities that people “see” are actually what comes next. Maybe they’re the dead welcoming us maybe some sort of extra-dimensional beings that are trying to communicate with us but we can’t see them until we die, so on dmt it would be like what happens when you die but you aren’t dead yet so this other realm doesn’t make a lot of sense to us. These things that our brain usually can’t perceive possibly even what the true world looks like feels like, etc, could even be unlocked by using dmt. People say that with dmt it’s almost like a color filter is over their vision, that somehow their vision has increased in saturation ten fold, things seem “more real” than they do in reality. Of course that would be on lower doses because dmt is one of the most powerful and most common psychedelic in the world because it’s produced in our own bodies. I just feel that we need to do more research into that topic and truly find out if indeed this alternate realm may be more than just a dream world. This is mostly speculation of course and we really don’t know that much about it yet because dmt is still illegal but there are factual things in this ofc, most of this I was able to put together because I ate edibles and I have adhd and after the high calmed down, it was like my mind was so much clearer so I apologize for my long rant, I hope someone finds this interesting or worthy of a conversation, thanks for coming to my TEDxTalk I suggest checking out psyched substance on YouTube as he does a very good job at explaining how different drugs affect you in both good and bad ways, he also has guests on the show and they do demonstrations and walk you through what they are experiencing it’s all very professional.

    1. Not sure what TEDxtalk you are referring to but you have obviously had an interesting time checking out this post!

  13. There will never be colors that we’ve never seen before because we can only see colors on a limited spectrum. Even by “training” our eyes, what we will see is what we are capable of processing with our 3 cones. The blue/yellow becomes an almost bluish grey and the red/green becomes an ugly brown.

  14. I am a novelist and like to write sci-fi. Along this line I’ve been fascinated by H.P Lovecraft’s “A Color Out Of Space” and reading this story got me thinking about what an “unearthly color” might actually be like. I also read a science magazine article about the supposedly “forbidden” colors of red-green and yellow-blue. I’ve found that if I stare at a color shield of pure red and a color shield of pure green and cross my eyes so that the crosses in the middle of each shield line up, I can see an actual reddish green, not a mud color, but a red with greenish tones I call “hot olive”. With the yellow and blue shields, I can line them up and get a hue I call cold lemon, not green, but a hue that’s yellow with tones of blue.

Leave a Reply

Your email address will not be published. Required fields are marked *