http://circles.sytes.org/

What's even cooler about that optical illusion, aside from the movement, is the difficult-to-shake perception that the images are spiral patterns, when they're not. They're concentric circles, but something about the illusion makes you perceive them as spirals.

This is my all-time favourite optical illusion:



Yes, open up Photoshop and check it with the paint-dropper if you must!

Gareth

This is my all-time favourite optical illusion:

???????????????????????

Yeah, doesn't that one just totally blow your mind? I love that one.

Wild. I had to prove it to myself...

ARRGH

If I can't trust my eyes, how can I trust the TV?

Am I just thick? I don't see it at all.

Oh NO WAY!!! I'm freaked out.

Is there a website with these things? I remember when I was younger seeing several billboard adverts (for cigarettes I think) with the impossible structures with wooden triangles etc. They amazed me at the age of 7 - and still do!

Just search for "optical illusions" - there are hundreds out there, but these are by the same author as the one above - I have actually seen them before, but the one above was emailed to me:

http://web.mit.edu/persci/gaz/gaz-teaching/index.html

This site seems to have quite a few varied illusions:

http://www.skytopia.com/project/illusion/illusion.html

Gareth

That second site is extremely cool, there are several optical illusions I have never seen before, and I have seen a lot of them. Check out "vision distorter", it is one of the most amazing and trippy illusions ever.

I don't feel so good....

Too much!

-Zeke

AAARRRGGHH!!!

I'm sure it's a static image. Almost.

booo, I can't get vision distorter to work!!

I don't feel so good....

I posted that really late last night and didn't look at them at the time because I knew I would feel dodgy!

Gareth

Dragging up an old thread here, but found some more awesome illusions of the same type:

http://www.lottolab.org/Colour%20illusions.html

The one on the bottom left is particularly stunning! Click the "illusions" button for more categories.

Gareth

More optical oddities!

The green and blue are the same colour.

Now that is weird! A quick cut and paste in MSpaint confirms this.
Can someone explain it? I'm presuming that it is the other colors that are tricking the mind.

That is truly odd. I would have thought that the lines in-between the green spiral were affecting how I saw that color, but that's the real color. I can't figure out how the other spiral turns blue.

Could it maybe have something to do with how the computer renders the image? I only ask because when I saved that image to my desktop, in Windows 7 it creates a little icon to show what the image is of, and when it's shrunk that small, all those little in-between lines are lost, and all I see are blue and green spirals on a pink background. When I bring that shrunken image into an image editor, they are definitely green and blue.

Uhh. What part exactly is supposed to be blue? I see green, purple, pink and orange...

Uh oh!

The spiral that begins at the top-left is supposed to appear blue.

*edit*
At least, I gather it is!

I think my colour blindness is kicking in here. All I see is a slightly lighter shade of green there.

Yup. That's what it is.

I was confused until I viewed it magnified. At first glance, it appears as though the orange stripes cross both the green-looking spiral and the blue-looking spiral. But that's not what they've done.

The orange stripes cross the green-looking spiral, but it's the *magenta* stripes that cross the blue-looking spiral. Both spirals are actually green, but the magenta shade "overloads" the color receptors in your eye, shifting that spiral towards the blue end of the spectrum, making it appear cyan instead of green.

If you look closely, you'll even notice that the green-looking spiral appears to have a faint cyan halo at its edges where it touches the magenta stripes.



I don't think so. I think if you saw the same image printed in vibrant-enough inks, you'd get the same effect.



That's because it blurs the image as it reduces its size. Blurring the image gives you the same results because the adjacent colors smear together, essentially producing the same effect that the color receptors in your eye are experiencing.

Actually, I see that the cyan-looking spiral has a green halo...

If you see green, purple, pink, and orange, then I guess you're getting a special illusion just for you. Only three colours are used in that image.

Peter

Okay. Looking at it more closely and during the day pink = purple... so yeah... 3 ><

Um. On rereading my post it sounded a bit snarky, which I didn't mean. I really just meant to say how interesting it was that someone who's colourblind sees a related, but different, illusion in the same image.

Peter

Oddly enough, the orange spirals appear to be pink towards the center for me, too. And I'm not colorblind at all. It seems to have to do with the perceived width of the stripes. If I get closer, less of the orange appears pink and vice versa.