APOD illusion

[Kevnool (Kev)]

http://apod.nasa.gov/apod/ap091004.html

Saw this on APOD i kept saying noway.
Then i tried the ultimate test saved it and opened it with paint and linked them and well i was proved wrong....again.

Cheers Kev.

[Esseth (Alan)]

Damn i love stuff like that, in fact i was just looking at the moon as it came over the horizion and looked huge lol

[leinad (Dan)]

That is cool!!

[DavidU (Dave)]

There are only 4 squares with the same grey scale.2 of which are A&B.
The green cylinder is there to distract your grey scale balance.

[MrB (Simon)]

I saw something similar to this a few years ago at a museum.(Powerhouse or Deutsches in Munich or Scitech in Perth... can't remember)

It was a section of wall painted grey with a single rope hanging down the middle of it... if you moved the rope you saw it was hiding a distinct line where two quite different shades of grey met and the wall was now suddenly very different!

[dpastern (Dave Pastern)]

Well, that hurt my eyes. Squinting helps. Had me fooled though. Shall test on my workmates tomorrow!

Dave

[Robh (Rob)]

Great illusion.
I was unconvinced until I cut and pasted the squares together.

Regards, Rob

[AlexN]

I've seen that posted on these forums before with regards to monitor calibration... very cool illusion.

[erick (Eric)]

Yes, I had fun with my work colleagues today. Finally printed it in colour then folded it to line up the two squares - they couldn't believe it.

Then I asked for a random number between 1 and 1000. No-one suggested anything like 111, 123, 456, 888 - no, they are not random, they say!

Ah, the "educated" human brain is a fascinating thing.

[RB (Andrew)]

Originally Posted by AlexN

I've seen that posted on these forums before with regards to monitor calibration... very cool illusion.

Yep, I posted a thread about monitor calibration using this illusion.

If you're into image processing, this illusion shows how you can't fully depend on adjusting the levels using just sight alone and say Adobe gamma.
There are too many outside variables that can skew the result.

The best way to calibrate a monitor is to use dedicated calibration hardware like the Spyder Pro, Huey, EyeOne or ColorMunki.

It's an amazing illusion though, I couldn't believe it either at first until I checked the grey values in Photoshop.

[dpastern (Dave Pastern)]

I agree about the calibration tools. Any serious photographer should be using one.

Dave

[avandonk]

Her is another one, Both flat surfaces have the same brightness.

From here
http://www.uq.edu.au/nuq/jack/rivalry.html


Bert

[danielsun]

Thanks for that Kev, I love this stuff.
Bought an excellent book a few years ago called( The Fantastic world of Optical Illusions) by Al Seckel with 300 pages of amazing illusions.
That is another incredible one Bert, So hard to beleive!!

Cheers Daniel.

[bloodhound31]

That's great Kev, thanks for posting that.

Baz.