Luminous Landscape Forum

The Art of Photography => The Coffee Corner => Topic started by: tom b on August 21, 2011, 02:22:29 am

Title: Great illusion
Post by: tom b on August 21, 2011, 02:22:29 am

You won't believe your eyes in this video (http://www.allvoices.com/contributed-news/10058276/content/86145051-shade-illusion).

Cheers

Tom

Title: Re: Great illusion
Post by: feppe on August 21, 2011, 05:34:16 am

Haven't seen this done in real life like this before, really nice!

Title: Re: Great illusion
Post by: Eric Myrvaagnes on August 21, 2011, 09:05:41 am

Quote from: feppe on August 21, 2011, 05:34:16 am

Haven't seen this done in real life like this before, really nice!

Likewise! Much more convincing than the usual 2D illustrations where you have to use the eyedropper to verify it.

Title: Re: Great illusion
Post by: aduke on August 21, 2011, 01:12:24 pm

A nice illustration of the illusion. It would have been even more convincing if the squares had been shown to be completely opaque.

Alan

Title: Re: Great illusion
Post by: tom b on August 21, 2011, 04:25:24 pm

Here is a screen grab from the illusion. I can't see any transparency.

(http://1.bp.blogspot.com/-pLokNSVqlQA/TlFpQYw-BDI/AAAAAAAABBM/6jDNUdsl0dA/s1600/screen_grab.jpg)

Cheers,

Title: Re: Great illusion
Post by: aduke on August 21, 2011, 05:43:30 pm

It does appear from that frame that there is none. But this is an illusion, after all.

Alan

Title: Re: Great illusion
Post by: tom b on August 21, 2011, 06:20:06 pm

This is what an optical illusion (http://en.wikipedia.org/wiki/Illusion) is. The only thing that is tricking us is our brain.

I copied the image on the link's page and pasted it into Photoshop. I then copied the two squares and moved them to the right. The result is shown below:

(http://3.bp.blogspot.com/-mNhI6y8meJ8/TlGDbtWGA4I/AAAAAAAABBQ/UxhrXzkRFPw/s1600/illusion.jpg)

Try it for yourself.

Cheers,

Title: Re: Great illusion
Post by: Eric Myrvaagnes on August 21, 2011, 09:06:35 pm

And just to verify, I popped this image into Photoshop and placed the hand just to the left of each of the A's and B's and read off the RGB values from the "Info" panel.

As expected, for both A tiles, I read R=G=B=139. But for the left hand B tile (the one still on the board, in the shadow) I read R=B=G=139, while for the right hand B tile (the one off to the side) I get R=G=B=139, which is 'obviously' much higher than 139.  ???

Conclusion: You can fool some of the people all of the time, but you can only fool Photoshop some of the time.  ;)

Title: Re: Great illusion
Post by: BobDavid on August 26, 2011, 09:30:04 am

Neat

Title: Re: Great illusion
Post by: BernardLanguillier on August 28, 2011, 05:46:54 pm

Nice!

It is a great confirmation of the remarkable inability of our brain to assess realistically absolute values, yet alone to remember them.

Audiophiles wouldn't like it! :)

Cheers,
Bernard