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Topic: Great Optical Illusion
Message: Posted by: Looch (Apr 13, 2007 12:55PM)
Personally, ive never seen this one before and its a belter!

http://www.youtube.com/watch?v=F9XlQ1IjmZU&mode=related&search=

Ps its not a "make you jump out of your skin" hoax/trick so please try and do this properly and don't fast forward to the end of the video.

all the best
Message: Posted by: wordSMITH (Apr 13, 2007 12:59PM)
That is really rather amazing!
Message: Posted by: Josh Zandman (Apr 13, 2007 01:00PM)
That is great!
Message: Posted by: wordSMITH (Apr 13, 2007 01:01PM)
The first time I watched it, I wasn't actually paying the proper attention, so the shift went straight from the inverse colours to black and white. Which made it seem fantastic the second time I watched!
Message: Posted by: Looch (Apr 13, 2007 01:02PM)
(pasted)

This optical illusion relies on a principle called "Chromatic Adaptation".

An object may be viewed under various conditions. For example, it may be illuminated by the sunlight, the light of a fire, or a harsh electric light. In all of these situations, the visual system indicates that the object has the same color: an apple always appears red, whether viewed at night or during the day. This feature of the visual system is called chromatic adaptation.

Have you ever entered a movie theater on a sunny afternoon? The room probably appeared completely dark but as your visual system adjusted to the reduced level of light you were able to see better after a few moments.

This "adaptation mechanism" allows our eyes to recover from an oversensitivity to a particular stimuli. "Chromatic adaptation" occurs when our eyes adjust to certain color stimuli. Chromatic adaptation is one of the more easily fooled aspects of vision, and is prone to some of the most spectacular optical illusions.
Message: Posted by: Andini (Apr 13, 2007 01:03PM)
Very cool, looch. A long time ago I came across a similar illusion: http://www.johnsadowski.com/big_spanish_castle.php When I first saw it, it freaked me out. It was [i]the coolest[/i] optical illusion I'd ever seen. That link actual links to another site that shows you how to make this illusion out of any photo.

I think this youtube one would have been interesting if someone broke the balls after the change. Then everything would out of whack!
Message: Posted by: Looch (Apr 13, 2007 01:09PM)
Thanks for the link Andini, will be making my own now!!
Message: Posted by: Andini (Apr 13, 2007 01:13PM)
[quote]
On 2007-04-13 14:02, looch wrote:
(pasted)

This optical illusion relies on a principle called "Chromatic Adaptation".

[/quote]

I think it might also have to do with "retinal fatigue." This is what happens when you look at the funky-colored American flag, and when you look at a white surface, the colors are correct. Simply put, when staring at a colored image, you "wear out" the respective cones on your retina, so when you look at a white surface, the other cones take over and produce the OPPOSITE color. The same is true here. You're looking at a colored image that's opposite the colors of the true image, so when the image changes, your other cones take over and fill in the uncolored areas in the new picture.
Message: Posted by: magicmind (Apr 13, 2007 02:52PM)
"rectal fatigue"? ahh, sorry andini, must have stared at the dot to long before reading your post :D

COOL stuff...would make a nice avatar too
Message: Posted by: rowdymagi5 (Apr 13, 2007 03:45PM)
Very Cool!
Message: Posted by: Dave V (Apr 13, 2007 05:06PM)
Here's a creepy one for you:

[img]http://www.davevmagic.com/forumpix/spider.gif[/img]

This is a perfectly stationary image with some grey scale work going on.
Message: Posted by: fishwasher (Apr 13, 2007 05:16PM)
That spiders pretty cool!
Message: Posted by: Looch (Apr 13, 2007 05:36PM)
That spiders not stationary...its just crawled across my keyboard! :)
Message: Posted by: Andini (Apr 13, 2007 06:39PM)
You're freakin' me out, Dave! That's wicked!
Message: Posted by: Montethrower (Apr 13, 2007 07:24PM)
So awesome. "The inner machinations of my mind are an enigma." --Patrick from Spongebob.


So cool, again...

Best,
Monte
Message: Posted by: Slim King (Apr 13, 2007 08:49PM)
Nice!!!!
Message: Posted by: Xiqual (Apr 13, 2007 11:10PM)
I don't see the spider moving. Help!!!
James
Message: Posted by: Dave V (Apr 14, 2007 12:01AM)
Some browsers stop animations after a certain number of repeats. You can either refresh the page, or right click and save it to your computer and view it there. You'll need to either open it from a web browser or a viewer capable of displaying animated gifs or you'll only see the first frame.
Message: Posted by: Naidu Gautama (Apr 14, 2007 01:01AM)
Very very nice !
Message: Posted by: RickThibau (Apr 15, 2007 03:26PM)
Cool! I was waiting for a prank! :oS
Message: Posted by: TomKMagic (Apr 15, 2007 03:43PM)
You can even set it as your desktop wallpaper, and most animated .gif files will actually cycle continuously. Pretty cool stuff.
Message: Posted by: MichaelSibbernsen (Apr 15, 2007 11:10PM)
Here is another eye fatigue / persistence of vision optical illusion you all may enjoy.

Focus on the tip of the nose, the chin, or the pendant around the neck. The picture will alternate every 10 secs.

Michael

http://tinyurl.com/2fo2s5
Message: Posted by: MrHyde (Apr 16, 2007 12:31AM)
I prefered the pendant

:)
Message: Posted by: TomKMagic (Apr 16, 2007 05:08AM)
[quote]
On 2007-04-16 01:31, MrHyde wrote:
I prefered the pendant

:)
[/quote]

The tank top works even better. I just tried it.
Message: Posted by: Hill (Apr 16, 2007 07:54AM)
Fantastic
Message: Posted by: wordSMITH (Apr 17, 2007 05:30AM)
Indeed: that one is rather good!
Message: Posted by: David de Leon (Apr 17, 2007 02:09PM)
I don't think the mechanism at work in the pool table illusion is "chromatic adaptation". I think this works by means of an afterimage (of the coloured balls) being superinposed on top of the image of the black and white balls. You can demonstrate the fact that you have formed a coloured afterimage by looking at a white surface after staring at the coloured image for a while (about the duration set in the film). You should then also see the coloured pool balls.
Message: Posted by: MichaelSibbernsen (Apr 17, 2007 03:33PM)
You are right david; It works by a combination of Retinal Fatigue and Persistence of Vision.

For those interested in making one of these images, use your favorite editing software (Photoshop, Elements, Graphic Converter, etc.) and follow the steps below. These were used to create the young lady illusion linked-to above.

1. Layer two identical images.
2. "Greyscale" one image (i.e. make it B&W), and "Invert" the other (i.e. make it a photographic negative).
3. Produce an Animated Gif with a 10 sec. loop.

Michael
Message: Posted by: Bill Hallahan (Apr 17, 2007 05:12PM)
For some other less striking, but nonetheless cool examples, go to this [url=http://home.wanadoo.nl/paulschils/12.00.htm]page about Chromatic Adaptation[/url].
Message: Posted by: Andini (Apr 17, 2007 05:27PM)
[quote]
On 2007-04-17 16:33, MichaelSibbernsen wrote:
You are right david; It works by a combination of Retinal Fatigue and Persistence of Vision.
[/quote]

As far as I was aware, Persistence of Vision is what is at play when viewing film or animation. Because the images are not rapidly changing in this illusion (the pool table...not the spider), I don't see POV's role in the optical puzzle.

This talk of explaining the illusion through retinal fatigue sounds strangely familiar...
Message: Posted by: MichaelSibbernsen (Apr 17, 2007 05:43PM)
Andini,

Since the retina is "retaining an image" from one point in time to another, it can be seen as a form of Persistence of Vision. Regarding the phenomenon as used in frame motion; there has been for some time a debate whether this is even an accurate notion. There in a nice article found here; http://www.uca.edu/org/ccsmi/ccsmi/classicwork/Myth%20Revisited.htm

And yes, you did mention the Retina Fatigue above. My brief explanation came from another more in-depth thread made about a year ago on another board (by a variety of authors) where I dissected John Sadowski's Castle Illusion. Mine was not derivative of your post; apologies if it seemed that way.

Michael
Message: Posted by: MichaelSibbernsen (Apr 17, 2007 06:25PM)
Here was my original post made last June on another board. I thought it may prove interesting to the folks reading this thread. Be sure to take a look at the wonderful Spanish Castle Illusion (linked to by Andini above) before going further. This was posted after a thorough explanation of the illusion of provided, and used only to illustrate those points.


---------------------------


Below are the four images (2 real, 2 virtual) that you experience while viewing this illusion.

1) The Real Black and White

[img]http://homepage.mac.com/magicshow/castle/bwcastle.jpg[/img]



2) The Real Negative Color Image

[img]http://homepage.mac.com/magicshow/castle/invertcolorcastle.jpg[/img]



3) The Virtual Inverted Negative (i.e. Positive) Color after-image that appears on your eye due to "retina fatigue". (To create this image, I color-inverted #2)

[img]http://homepage.mac.com/magicshow/castle/colorcastle.jpg[/img]



4) The Virtual combination of #3 and the #1 that appears by superimposing the after-image on your retina with the actual B&W. (To create this image, I gave #3 a 35% transparency, and laid it on top of #1)

[img]http://homepage.mac.com/magicshow/castle/newcolor.jpg[/img]
Message: Posted by: Lawrens Godon (Apr 18, 2007 03:43AM)
Thanks for the links!
That was pretty amazing ^^
Message: Posted by: DanielSkahen (Jun 20, 2007 11:22AM)
Very awesome, great stuff.
Message: Posted by: Jonathan Townsend (Aug 7, 2007 01:09PM)
Thanks.

Also suggests that latent / negative image formation is part of how we detect edges in our visual perception.
Message: Posted by: todsky (Apr 11, 2008 12:42AM)
Amazing pool table and castle illusion! Thanks for those. And the tank-top.