Color tile optical illusion

You might have seen this shaded gray squares illusion before. Squares A and B are the same shade of gray. (It was created by Edward H. Adelson, Professor of Vision Science at MIT.

Here's a similar illusion with colored squares. The "blue" tiles on the top face of the left cube are the same color as the "yellow" tiles in the top of the right cube.

Don't take my word for it. Use an image editing program with a eyedropper to see for yourself. I used Photoshop's eyedropper tool to take 5x5 samples and found that both the "yellow" and the "blue" tiles are C:50 M:40 Y:40 K:5.

Take a look at the brown tile in the center of the top face and the yellow tile in the center of the side facing slightly to the left. They're the same color.

UPDATE: The color tile illusion is one of many excellent illusions created by R. Beau Lotto.

• [ryuthrowsstuff]

  that checker shadow illusion is rather interesting. the first thing that popped into my head was photography. most the intricacies of exposure and lighting revolve around the fact that film doesn’t do what our brain does in just this situation. you often have to compensate with lighting. or expose for in between square a and square b to get a somewhat similar image.

• [Antinous]

  Infinite Decay,

  My bad, but it’s the gradient effect overall that renders us incapable of perceiving it.

• [OM]

  …Yeah, but these guys aren’t answering the most important question: what’s the minimum number of slice turns required to solve the cube?

• [WadeFranklin]

  Edwin Land (inventor of the Polaroid camera) investigated this effect during his research into color vision. See “The Retinex Theory of Color Vision,” Scientific American, Dec. 1977. Land’s theory was that the brain uses cues from surroundings to maintain color constancy of objects.

• [ozten]

  That’s a great example of color theory. Joseph Albers taught many of his students these techniques, from a magic rather than a science perspective.

  You can reproduce this effect with three colors if your willing to forgo the 3d / photo-realistic fun.

  http://en.wikipedia.org/wiki/Joseph_Albers

• [Anonymous]

  Those images are from Discover magazine. I just wanted to point that out since nobody seems to have credited them:

  http://discovermagazine.com/2004/feb/neuroquest/

• [arkizzle]

  #34, EGYPT URNASH was right. that was kind of lengthy :p

• [Kmo55]

  I thought this was totally false by just looking at the picture but with the eyedropper I found it to be true. This still doesn’t make sense to me though, since the A tile obviously looks darker than the B tile.

• [Squashy]

  Yeah, your brain basically does an internal “white balance” on images it receives to compensate for light colour. That’s why things don’t look all orange to us when we are indoors at night, under yellow iridescent light.

  Actually, our eyes are a bit crap, and the reason we feel like our vision is pretty good is largely because our brains are really good at filling in the blanks and doing image-enhancement processing on the raw data. There’s lots of optical illusions around that exploit our brains’ image-enhancing. The ones that demonstrate the blind spot in the centre of our vision (where the optic nerve connects to the back of our eyeball) are particularly spooky.

  It makes you realise just how helpless you are to turn off your brain’s filtering and actually see what you are really seeing.

• [Takuan]

  explains a lot when you drop acid

• [stagendogs]

  In case of colored ones I can actually see that they are the same.

• [strumpet windsock]

  I found another way to break the illusion.

  Stand back from the monitor and try to imagine A, B, and the same-coloured squares next to them floating in a separate level above the rest of the grid.

  If you can do that (like bringing the image out of one of those 3-D pictures) you are longer influenced by the shadow of the cylinder and the squares are very clearly the same shade; it popped out at me quite suddenly, along with two other squares at the bottom of the grid which are also the same colour.

  Anyone else see it, or did I just take too much acid?

• [Antinous]

  …did I just take too much acid?

  Like that’s possible.

• [Squashy]

  “So the light square ends up darker in the image because it’s in shadow–so what? We’re smart enough to correct for the shadow”

  The point is that this correction is done unconsciously, and it is very difficult to switch it off. Even when you know that the two areas are objectively the same shade, your eyes won’t “believe” it unless you concentrate very hard.

• [Squashy]

  “So the light square ends up darker in the image because it’s in shadow–so what? We’re smart enough to correct for the shadow”

  The point is that this correction is done unconsciously, and it is very difficult to switch it off. Even when you know that the two areas are objectively the same shade, your eyes won’t “believe” it unless you concentrate very hard.

• [Antinous]

  The point is that this correction is done unconsciously, and it is very difficult to switch it off.

  It’s not psychological. It’s eye physiology. Which would indeed be very hard to switch off. You’d have to consciously control your rods and cones.

• [searconflex]

  Thanks for the advice Strumpet… I’ve now found that if I just stare a hole through ‘B’ it will slowly darken and reveal itself to be the same as ‘A’. Tres cool illusion, and thanks to all for the links.

  Wondering if it would be as effective if the column was a different color? What is the significance/purpose of Green here? Anyone?I’d experiment myself but I suck at photoshop………..

  no, really, I do.

• [Marsupial]

  Joe Mommasan did it exactly right. Forget about Photoshop, eyedroppers, and CMYK values. Print out the pictures, and break out the scissors. The illusion disappears as soon as you make the first cut separating the colors-in-question. I remember the first time I did this — no one would believe me until I physically cut everything up and dragged the blocks together. Take a few copies out to a bar and score some free booze or something.

  And, no, you cannot fully trust anything you see. Your reality is all based on your perception.

• [Streph]

  The Principles of Harmony and Contrast of Colours – M.E. Chevreul

• [Adam]

  this is the craziest optical illustion i’ve ever seen. for the first time in my life i can’t believe what i’m seeing. i eyedroppered the checker image in photoshop and confirm that i’m getting equal shades of grey. but my eyes just don’t agree. it’s mad science sorcery! heresy, i tell you!

• [Adam]

  wait… hold your hand over the cylinder and squint your eyes. closest i’ve been able to come to convincing myself that the shades of grey are the same (without means of scientific proof). amazing illusion.

• [CharlesV]

  The video for “Golden Cage” by Elrlend Øye’s band Whitest Boy Alive has several of these optical illusions featured. Putting them in motion lets you “prove” to yourself much easier though:

  http://www.youtube.com/watch?v=bOP37A1EhEs

• [Anonymous]

  That is amazing and sick. How can I believe anything I see????? AAAARRRRGGGHHHH!!!!!!

• [nex]

  Mark, measuring the colours in CMYK space is not so good, because different combinations of CMYK values can add up to the same colour. RGB or HSB would be better, firstly because of that, and secondly because in RGB you’d see that the individual values are identical (disregarding the tiny aberrations caused by artefacts) and in HSB you’d see that saturation is 0.

  Take a look at the brown tile in the center of the top face and the yellow tile in the center of the side facing slightly to the left. They’re the same color.

  Wot? The yellow tile … (there’s five of them …) Oh! You mean the ORANGE tile! Well, yeah. Brown is essentially a dark orange, or, as a painter or colour theorist would say, a shade of orange (a shade is some colour mixed to some extent with black, as opposed to tints, which are colours mixed with white), which makes perfect sense when you look at the picture and see how the orange tile is in the shadow, shaded, while the brown ones are in bright light.

• [Anonymous]

  i like optical illusions they r awesome

• [Jay Livingston]

  You don’t need Photoshop and eyedropper. I copied the cubes graphic and pasted into Paint, then used the “eraser” to white out everything but the blue and yellow cubes. The interesting thing was how much erasing I had to do before it finally became clear that they were the same color — a sort of gray. Even with very small bits of other nearby colors, they looked different.

• [Sam]

  I’m gonna go ahead and disagree. I see two different shades of grey, I see blue squares and yellow squares, and thats brown and kind of an egg yolk there at the bottom.

  I don’t believe in optical illusions, now that I know about quantum physics, no matter how many copies of photoshop you throw at me.

• [rawbear]

  The picture of the two side by side cube is also a good one for 3D illusion. If you look at it a bit cross-eyed (some practice necessary…) you will see the cube in 3D. It’s usually done without colors but also works in this case because of the careful color choices.

• [KafirCake]

  It’s crap like this that tells me my designer was more negligent than intelligent, what a wanker.

• [larisa0001]

  That is amazing; I actually verified it in Paint, and it is the same color, but my eyes still don’t agree. Wow.

• [Anonymous]

  Argh! And I can’t make it look the same, it still looks different to me.

• [strumpet windsock]

  Try squinting – then you can actually see that they are the same.

• [Takuan]

  maybe he was just drunk that day

• [Egypt Urnash]

  (lengthy discussion of the several possible readings of “the same color” and how this is as much about language as it is about the human visual system goes here)

• [wormspit]

  On the low-tech side, there’s an artist’s trick that helps with finding the relative colors and values of things… block the surrounding colored or shaded with your fingers, and you get a truer sense of what color the spot really is. It removes the context. It helps a lot in picking the right paint color. Some people even use a piece of cardstock with little holes cut out of it, and various shades or values surrounding it so that you can see where it falls. Like this: http://www.dickblick.com/zz049/47/

  If you can hold up your fingers so that all you see is finger between the two pieces you’re comparing, they’re visibly identical.

• [BKMD]

  Hiya Mark:

  I sliced out the A square and put it next to the B square

  I still can’t “force” my eyes to see that they’re equal in the top image.

• [mynameisbob]

  The blue yellow colours are both gray. Look in RGB space.

  The brown yellow one is good though. Cut out the brown tile and slide it next to the yellow one. The change is impressive.

• [Mark Frauenfelder]

  (short discussion about how a tube of paint that could be used to paint the brown tile could also be used to paint the yellow tile goes here)

• [plousia]

  Holy McCrappers, that’s crazy. I, too, sliced out the A and B squares and put them next to each other, as well as using the eyedropper tool, and sure enough, they’re identical. What an amazing illusion.

• [Antinous]

  (arch reference to Schizopolis)

• [Nora]

  Alternatively you could use the totally awesome ColorZilla plugin for Firefox (https://addons.mozilla.org/en-US/firefox/addon/271 ).

• [jere7my]

  The image is a JPEG, and I think the compression diminishes the illusion a little. The squares in question aren’t one color — they’re patchworks of pixels, and some pixels of the “yellow” squares on the right are in fact a warmer gray than the “blue” pixels on the left.

  That said, it’s a very powerful illusion. I verified it by snipping a little rectangle from one of the “blue” squares on the left and dragging it next to one of the “yellow” ones on the right, and I’d've sworn that the little clipping changed colors as I dragged it across the boundary. I swiped it back and forth a few times, and it sure looked like it was flipping from blue to yellow and back.

• [Infinite Decay]

  I love that checker shadow illusion. Just to give credit where it’s due, it was created by Edward H. Adelson, Professor of Vision Science at MIT.

  And I came here to say what jere7my already wrote — a problem with all of these images as they appear on this page though, is that they are saved in JPEG format, which uses lossy compression and alters the colors so that the intended illusion is not exactly true. (When I check the color values in the images, I can get different values even in the same tile.) It would be more accurate if a format such as GIF or PNG were used.

• [Antinous]

  When I check the color values in the images, I can get different values even in the same tile.

  That’s the point. They’re gradients. Humans don’t perceive gradients very well. Generally, carnivores excel in edge definition (better for hunting) and herbivores excel in gradient definition (maybe better for picking out grains or edible vegetation).

• [Anonymous]

  If you look above the cylinder and focus just behind the image, you can beat the illusion, as you’re looking at it directly and percieving it as an image of a 3d scene.

• [mathus]

  I don’t get what the fuss is about, in bauhuas painting training you have to learn to do optical illusions like this with paint. I did a piece of sculputure that actual has a color in the showdow that looks like the color on top but are two differnt colors. I’m not impressed

• [sassifrassilassi]

  mathus isn’t impressed, folks. let’s delete this and all go touch ourselves while thinking about bauhaus and how awesome we are.

• [Takuan]

  let’s hook up some electro shock gear and see if the brain and eye can be “taught”

• [PopeRatzo]

  Naw, it can’t be.

  You’re messing with my head, Mark.

• [jjbuilder]

  by the way, those images are by beau lotto:

  http://www.lottolab.org/Brightness%20illusions%20page.html

• [jjbuilder]

  sorry those *other* images…. (apart from the cylinder as noted above)

• [David]

  That is pretty crazy. Albeit it is less impressive if you are a tad color blind.

• [Egypt Urnash]

  Yeah, that’s pretty much what I was aiming for, Conkle. It really comes down to deciding what you mean by “the same color”; it is as much about that as it is about the color-correction routines in our brains that we can’t turn off. Thanks for unpacking my meaning properly!

  As to Mark’s note about what tube of paint you’d use to paint the squares that’re the represented by pixels of the same grey color… well, any workflow I can imagine myself using pretty much has me mixing colors, throwing over translucent glazes, and so on, and never actually using one particular color. YMMV, of course; if you use a projector to deliberately keep yourself from parsing the whole image, you might well use the same paint on both.

• [Xodarap]

  I think people were too quick to dismiss the philosophical importance of the second post.

  First off, the existence of SURFACES is merely an optical illusion: there is no surface (there are none anywhere in the universe), there are no colors or shades thereof (ontological infection: no type, no token), and photoshop/paint are manipulating a completely different set of data than your subjective interpretation of an illusion of an illusion of an illusion…

  I will agree with #25: they ARE, in fact, different. These *images* only exist as such in my mind. If the colors (which also only exist in my mind as such) *SEEM* different (and all they are are “seemings”), then they ARE different. I’m NOT a subjectivist, but some things — like images and colors — are purely subjective. There are objective facts about these images, but photoshop is lying to you — the objective facts have nothing to do with color ;)

• [Joe MommaSan]

  I printed out the gray one and cut out the two little squares. Although I didn’t believe it until I actually saw them side by side, they’re the same.

• [Infinite Decay]

  @7 Antinous: Actually, no, that isn’t the point. If you check the original image from the checker shadow illusion, you can determine that the color within the two tiles A and B are exactly the same color value (RGB: 120, 120, 120), and consistant over the entire square. The illusion comes from the contrast between these squares and the rest of the image surrounding it, not differences within the square itself (which are an unintended consequence of JPEG compression in the images on BoingBoing).

• [Conkle]

  I think commenters are missing the distinction here, which Egypt Urnash pointed out all the way up in #1. Our brains and eyes–correctly!–perceive that A and B are different shades on the modelled object. One is a dark square, one is a light square. (Compare adjacent tiles to confirm this.) We don’t care what color paint is needed to paint the “picture”, we care what color paint is needed to paint the chessboard or cube. So the light square ends up darker in the image because it’s in shadow–so what? We’re smart enough to correct for the shadow; it’s not like we don’t notice the shadow’s there.

  The distinction between “object” and “portrayal” is what Egypt Urnash was getting at with the question of language–our brains are concerned to answer the question of “what color is this object,” and answer that question correctly. The “optical illusion” interpretation misconstrues “shade of grey” and “color” as applying to the portrayal, the image, rather than the portrayed, the chessboard or cube.

  To put it more bluntly: if we’re in a linguistic framework wherein A and B are, in fact, the same shade, i.e. looking analytically at this JPEG, the correct answer to “Are squares A and B the same color?” is “What squares are you talking about? There are only a bunch of trapezoids there.” It’s the same layer of abstraction–if our color-correcting mechanisms are “illusion,” then so is perspective. As Wormspit reminded us, visual artists spend a lot of time learning to mimic both of these effects on two-dimensional surfaces–just like the 3D rendering software used to make these “illusions.”

  (Oh hell, if the point is “2D portrayals of a 3D world are illusions,” I’ll agree; I think we’ve known that for a few centuries now.)