Colour perception test

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  05 May 2005
Talking Good ones, Theresa and Jan-Mark!

Well, I think the next CG Challenge should be "The Blue Red Apple"! What do you think?
( ( ((DrFx)) ) )
  05 May 2005
These kinds of brain-teasers blow my mind.

I've heard of people being raised in a primitive setting in jungles and then they take these individuals into cities and they can't get around because their perception of depth is non-existent. So one day I was in a parking lot of a grocery store that was uphill from where I parked. I concentrated on the scene and worked at imagining the whole thing as a flat surface and I was merely climbing it to arrive at the doors of the store. Suddenly the whole thing flattened out and I had to stop walking because it was freaky looking... the brain is POWERFUL! I tried the same thing while riding a bus to work one morning and it can be repeated. I haven’t done that again though… its too crazy… I like my perception of depth
  05 May 2005

I guess that is what we see after all, a 2d image- the further away, the higher up it gets (if you're on the ground obviously). Strange how we learn to intepret that so flawleslly.

The miracle of God, eh?
  05 May 2005
Wow, these brainteasers hurt my head.

It boggles my mind that our brains view colour this way.
  05 May 2005
Relative Contrast

Relative Contrast

After reading this thread I was inspired to try something I've wanted to try for awhile now.
What if you increased the contrast of an image with each pixel being relative to its surrounding pixels. So that a gray pixel surrounded by black becomes white, but surrounded by white it becomes black.

Here is my test image

And the result

First I took the original image and made a blurred copy of it (to get each pixels surrounding pixels)
Then I subtracted the blurred image from the original image (results need to be unclamped, values below 0 darken the image whilst values about lighten it).
In order to tone down the effect a bit the results may be divided at this stage.

Then I added the original to the results of the subtraction.

Here is an example on a photo



This does a bit more than just changing the contrast in photoshop, because it works relatively it brings out details, where contrasting just adjusts the whole image.
Bringing out details can be bad in a lot of cases, for one it makes highly compressed jpegs look even worse and for two not many people like having their pimples standing out from the rest of their face in photos.
This process works to exaggerate the way the eye views differences in lightness/darkness relative to their surroundings.
This is may be available in some software packages I am not aware of. Or even photoshop.
  05 May 2005
The 3rd example of the color test is not correct...those two sword center part color values ARE different. To check that for yourself, do a screen capture of the image and check them with the Eye Dropper sample tool in Photoshop, I used a 5 X 5 sample rate. The others are pretty cool though as far as relative perception of tone goes...neat stuff...
  05 May 2005
Check out

Basically the fact that we still see "colours" in a variety of different lighting condition in the real world suggests that "percieved" colour and "real" color can be radiacally different. This probabily won't come as a surprise to us as artists - but what the theory suggests here is the fact that the images appear green is because there is a white border ...

Do not imply, however, that this means "all colour is relative", percieved colour can be relative - but true colours, their wavelengths, still exist ... colours are absolute, so to speak, relative to white.
  05 May 2005
yeah this stuff is scary

I used to I had my desktop in dark blue... Then I switched back to a neutral dark grey. It took a few weeks till I wasn't seeing yellow - Scarey huh.... Neutral colours from now on
  05 May 2005
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