Colour perception test

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Old 05 May 2005   #1
Thumbs up Colour perception test (blue red apples inside)

Saw this in another forum:

It shows how your colour perception is affected by the background of stuff. It really is amazing, try it!
( ( ((DrFx)) ) )

Last edited by DrFx : 05 May 2005 at 08:31 AM.
Old 05 May 2005   #2
That is pretty crazy. I've seen things like that before but it gets me every time.

I wonder if people with more developed color sense can 'see' this right away?
Old 05 May 2005   #3
That is mega cool!
Old 05 May 2005   #4
Wow, that was amazing. Very cool like thingy there.
Old 05 May 2005   #5
I'm more amazed at the fact that we are fooled by a 8-bit value range, are you going to tell me it never crossed your mind how many times an image had recurring colours after the artist has carefully thought up a colourplan or scheme.

We're talking 256 differeent greyscale intensities, that's all man.
modelling practice #1
Old 05 May 2005   #6
The human senses are pretty limited: Put those greyscale levels side by side in a gradient, can you tell the difference between them? No, it'll be one continuous gradient!
Also, can you tell the difference between 8-bit, 16-bit and 24-bit sound, coming from average speakers? Or between a good jpg and a tiff? A CD and an MP3?
( ( ((DrFx)) ) )
Old 05 May 2005   #7
Yeah actually most of the time or a lot of the time, also depends on the environmental noise and levels imposed on my senses, since they're more imporant to respond to.

But I do agree that without watching for the subtleties it could easily ellude me.
modelling practice #1
Old 05 May 2005   #8
We see the colors that way because we are constantly trying to correct the colors so they seem right to our brains.

A nice example would be Monet (french painter). He develpoped an eye disease which made him see things more red. He used to paint his garden and as the disease developed his painting went from normal green colors to reds. His brains were trying to correct the colors.
(edit: a link about this subject: )

That's why eye "malfunctions" are mostly discoverd fairly late, because we can't notice the degrading eyesight. The brain corrects most of the flaws by filling in the gaps.

Last edited by _slvl : 05 May 2005 at 07:11 PM.
Old 05 May 2005   #9
Originally Posted by DrFx: can you tell the difference between 8-bit, 16-bit and 24-bit sound, coming from average speakers?

hell yes i can. if you can't hear the difference between 8 and 16, there's something seriously wrong with your ears or speakers. 24-bit sound is often hard to distiguish from 16, but it's great to record in 24 or 32 bit, because you have plenty of headroom when editing the sound, so it won't degrade past the point where a human would notice... the same reason hdr images are usefull even though you can't actually see them on your monitor.

Old 05 May 2005   #10
also, in the last one it surprised me that it was denoted as a grey colour I thought for an iontstant that it really was blue. Would have made more sense to me actually. ANybody else saw a blue region there? Or am I a freak?
modelling practice #1
Old 05 May 2005   #11
hmmm on the third one I was seeing blue and yellow not grey and yellow. What's that mean? Am I broken?
__________________ - I'm available for hire.
Old 05 May 2005   #12
Thats amazing... Thanks for sharing... As for sound... I can tell the difference from compressed MP3s at 256 kbs comparred to the original... Me and my old roomy were pretty toasty one night and he said he could tell the difference... I have a nice system... Maybe thats the difference...I have KEF 104.5 studio monitors with audioquest midnight hyperlitz cables...He was correct... You can put your fingers GENTLY on the bass-cones which are 12" and the Mp3's bass is more sloppy... the in/out of the original recording is tighter. One really has to hone their perceptions but since the optic system is WAY more esoteric than hearing... The tests just work on everyone... I guess?
Old 05 May 2005   #13
Originally Posted by jmBoekestein: also, in the last one it surprised me that it was denoted as a grey colour I thought for an iontstant that it really was blue. Would have made more sense to me actually. ANybody else saw a blue region there? Or am I a freak?

i saw blue in there too, i'm gonna go exhange my eyes for new ones...
Old 05 May 2005   #14
This is an excellent example of how colors are relative, and questions like "What's a good skin tone color to use?" are completely futile.

Last edited by Lunatique : 05 May 2005 at 01:03 AM.
Old 05 May 2005   #15
If anyone is interested in scientific theories of image perception then this article on Image segmentation and light perception is applicable. It doesn't deal with colour but has similar optical illusions to the greyscale ones linked to above and a couple of videos.

I recently edited a paper that summarised the one linked above and it mentioned colour:

"The layers concept exemplifies a computational strategy known as inverse optics. The intensity at each point in the image is the product of a combination of factors: the proportion of light reflected by the surface at that location (called reflectance), the
intensity of illumination incident on that surface, and certain properties of the intervening
media, such as those of fog or filters. By the laws of optics these factors become entangled in the image. In principle they can be disentangled by hypothetical brain
processes that are inversely related to the optics of entanglement.

For example, a red book on the dashboard of your car casts a red reflection in the windshield. Through the reflection you perceive distant objects, including
green grass, in their normal colors. Light from the green grass and the red reflection physically mix to produce yellow. The yellow is observed when seen through a
small hole punched in a piece of cardboard held up so it blocks out the surrounding context. Without the cardboard, however, no yellow is seen, only the red and green
layers. The brain is thought to split the yellow light into the red and green layers using rules that invert the usual rules of color mixing. This is called scission."
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