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

13 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.

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