How subjective is our vision?

[fcalvo]

This is the best optical illusion I've seen so far. Made me open PS

to check, couldn't believe it.

<br><br>

Makes me ask myself how different reality might be to that what I

actually perceive through my own eyes.<div></div>

[will_perlis]

That's why it's important to avoid looking at pictures and only pay attention to numbers.

[andrew_rodney1]

There are a few good ones here as well:

 

http://www.colorcube.com/illusions/illusion.htm

[john_myers4]

Federico,

<p>

I knew what illusion it was going to be before I even opened the picture - I absolutely agree that it is the best I've ever seen. Makes you question your sanity! There are a lot of other good papers, articles, and illusions at the MIT site where I believe that one originated.

<p>

<a href="http://web.mit.edu/persci/">MIT Perceptual Science Group</a>

<p>

~John

[michaelkh]

Anyone who's ever done extensive cloning on a black and white digital image has seen this

one - you clone from one area to another, convinced the areas are broadly in the same

tones, and then find out they are not... Fascinating.

[andrew_rodney1]

Makes you wonder why some regular's around here swear by eye-ball calibration of their

displays....

 

Andrew Rodney

http://digitaldog.net/

[fcalvo]

Thanks John for the reference, it's very interesting. The following is and extract of the explanation of this illusion which I find revealing.

 

'As with many so-called illusions, this effect really demonstrates the success rather than the failure of the visual system. The visual system is not very good at being a physical light meter, but that is not its purpose. The important task is to break the image information down into meaningful components, and thereby perceive the nature of the objects in view.'

[fred_bonnett2]

Andrew:

 

Should not your photos be as subjective as your eyes --- most of us are not taking photos for machines but for ourselves and other people --- so unless your into forensic photography, record and reproduce what you see --- make your photos truly personal.

 

BTW how did you ever reconcile claiming 13 stops of exposure latitude for a film that kodak claims has 5 stops of latitude. Did your machines let you down?

 

Cheers

[johnclinch]

My wife was not confinced by the numbers

 

so we painted out the rest of the image in white

 

worth doing to watch b get darker

[jtk]

We've not established that everyone saw that the same way.

 

As well, that the illusion has not yet been discussed in relation to printing...presumably the reason for the exercise.

 

To take the point further: Within three test prints I (and many of us) can acceptably match (visually determined by random onlookers) anyone's digitally determined print of that image, using a random, reasonably functional monitor and my own PC and printer.

 

As photographers, aren't we concerned with output for purely visual appreciation, more than with closed-loop digital games? That illusion is just its own closed loop, after all.

[lad_lueck]

I had to crop out the shadow and look at it! Absolutely amazing image.

 

Now, maybe I didn't *really* see that UFO? :-#

[fcalvo]

John, that this exercise was done digitally doesn't make the conclusion less real. Our vision behaves the same whether we are looking at a screen or the real thing. I'm sure that if we could replicate the whole setting in a studio we would end up with the same result.

 

The point of this ?digital game? (at list for me) is to let us understand up to what point our vision can accurately perceive reality and that, as I see it has everything to do with visual appreciation. It was somewhat of a surprise for me to see such a different result between what I clearly saw as 2 very different shades of gray and the actual proof that they in fact were the same shade of gray.

 

There could actually be real applications making use of this effect at some point, who knows.

[jtk]

Federico, why would anyone assume our vision is identical on a monitor and in reality? A bizarre idea!

 

Optical illusions, to work, rely on reduced information. In other words, they work for illusion purposes by depriving us of the kind of information we'd invariably have "in reality."

 

This particular illusion is a lot of fun!

[fcalvo]

So you say it would be physically impossible to replicate this setting in the real world? Kind of like Escher's stairs?

 

I say that it is possible to replicate and that the perceptual effect would be the same.