A tw**t from Tom Chivers (via Matthew Cobb):
But it is right!Ā Phil Plait at Bad Astronomy proves that the colors are indeed the same, explains why they look different, and links to other amazing color illusions. If you look at the diagram carefully, you might be able to figure out why the blue and green are really the same.
I think that Tom is one of the better science journalists around – even if he does write for the Telegraph!
Green-pink and blue-orange juxtaposition.
If the green and the blue are the same colour, is that colour blue or green? Or is it blue-green (turquoise)? The orange stripes have something to do with it. I wonder what Daltonians see…
I took the image and looked at the colors – they are indeed the same color, and that is the one known on old computer monitors as “cyan.” It’s Red=0, Green=255, Blue=150.
I haven’t seen sufferers of Daltonism described that way since … the old (mad) king was on the throne!
But … but… but I saw it with my OWN EYES!
Blue and green. I don’t need to dig any deeper. I know what I saw; I know what I know. Stop trying to make me deny my own experience!
If you like, I know just the place to go to get some crackers that will pair perfectly with that whine!
And, as a bonus, you’ll get to hear some live music every bit as awesome as the stuff Jerry’s been flogging the past few days….
b&
Gaaaah!! It is true!. Zoom in with your computer, and you can see the blue stripes start to look green. Mask out the magenta stripes that interrupt the blue stripes to completely collapse the illusion.
What is real? Now I am not so sure….
The hues change with distance, as well – just move close to the screen.
Coincidentlly, I just read a little essay by Richard Dawkins entitled Redundancy Reduction and Pattern Recognition. That was a subject that Charles Darwin’s great grandson, Horace Barlow, had published on. The Dawkins essay is the third one in This Explains Everything: Deep, Beautiful, and Elegant Theories of How the World Works.
Stupid brain.
I have not looked into the cause of this one, but I provisionally think that the effect is related to the old ‘American flag’ illusion where looking at certain saturated colors causes the responding cone cells to shut down. This triggers misfire signalling by adjacent cone cells are sensitive to a different color, causing you to see a false color. I speculate that in this case the intense magenta stripes saturate the red cone cells in the retina, so they quickly attenuate their signalling to the brain.
The attenuated red cones cause adjacent blue cones to step up their sensitivity, and the result is that you to see a false blue color. This adaptation must happen very quickly so you do not notice it.
Impressive! š
That can’t possibly be the explanation. Those colours look different instantly, so it can’t possibly be a saturation effect.
It’s actually the brain changing the colour that’s actually there. The brain compares colour with the colour of surrounding objects. It works in the same way the checker board illusion works.
Yes, except, in this case, it’s not the mechanism that determines brightness / value based on shading cues that’s being played upon, but our sense of color temperature / balance.
Look very carefully, very critically at a styrofoam cup outdoors in direct sunlight. And take a photo of it to confirm what you’re seeing.
At a casual glance, there’s no doubt but that it’s white. But…the part in direct sunlight is actually yellowish and the part in shadow is bluish. (How well measurements from a photo match that will depend on how well your camera does at setting white balance.)
Now, move the cup in the bright shade under a tree. You still think it’s white, but it’s actually greenish. And hold it up near a rose, and some of the cup will be pinkish. Yet the cup will still look white to you.
Painters are acutely aware of this phenomenon, as are the more careful photographers. Color scientists, too, of course…but that’s about it.
Cheers,
b&
Yes, I used this blue shadow example in another post – your brain filters out all that stuff and sees what it needs to see. You start to recognize it when you do things like photography and notice the blue of the shadows (and then change the RAW image because it is annoying :))
If your shadows are too blue then either the color temperature is off or the saturation and / or contrast is too high.
The best way to set white balance involves building a one-off ICC profile of the scene, and is most impractical for most people. The next best way is to crank the saturation to its highest value and fiddle with the white balance knobs until the picture looks the least awful, then return saturation to normal. You’ll find that this method yields better results than a click white balance with even the most expensive white balance target. And, if you must use a white balance target that you click on, you literally must spend thousands of dollars to get something that’s superior to a styrofoam coffee cup.
Cheers,
b&
Yeah, I think it’s mostly because I have taken photos that are in a lot of shadow. I usually notice when I am taking the photo but adjusting the f/stop, speed or ISO is not an option if I want a non blurry, non noisy photo so I fix in post.
That’s a beautiful theory. š
Seriously, it sounds plausible. Well done. Do you work in vision?
Crazy illusion.
Hey, Jerry, I thought you said you read all the comments here. I posted a link to this illusion about a week ago in one of your earlier offerings regarding optical illusions
I said I TRY to read all the comments here but don’t always succeed. If I missed your post and failed to give you credit you feel you deserve, I apologize.
Maybe you subconsciously influenced him. Let’s think of how to plant or subconscious things….. š
If seeing is not believing anymore, then all the witnesses of all the miracles should keep their stories to themselves!
Are we all seeing the same spirals as blue and the same spirals as green? Seems just as likely that what appears blue should appear green and vice versa. Does the particular juxtaposition of blue and gree stripes depend on the individual brain? Does the brain “toss a coin”? How does one know that it is not actually green appearing blue? How does one know that the red and orange are actually other colors “masquerading” as red and orange?
Well, if one can’t believe ones eyes, then for sure one can’t believe just anything humans SAY, simply and solely because they SAY it. Apparently, visual eVIDEnce ain’t what it used to be, eh?)
Color science is quite clear on this: within the same types of minor variation that we see in other characteristics of humans, yes, we all perceive color the same way. There’re some big asterisks with respect to color blindness and the like; however, even then, the vision of such individuals can be extremely well modeled.
There has also been some recent work whereby a computer can reconstruct what an individual is looking at based on brain scans. While low resolution and very primitive, it’s more than enough to demonstrate that vision is entirely a process of the brain, and that the same basic thing is happening in everybody’s brain — again, with expected minor variations.
TL/DR: You can cross “qualia” off your list of things to ponder.
Cheers,
b&
I disagree with the assessment of this illusion: being a colour relationist, I’d say that they’re only the same colour in the *physics* sense of colour (wavelength, assuming constant monitor etc.). Subjective (psychophysical) colours of almost any appearance by manipulating background (which was constant in Newton’s experiments, etc.) and such. See _Color Ontology and Color Science_, ed. Matthen and Cohen.
Er one can provoke subjective, etc.