
Impossible colors - m0th87
http://en.wikipedia.org/wiki/Impossible_color
======
sudont
Back when I was a wee art student, I had a phenomenal printmaking professor
who was an expert in inks. One of her projects was a monotype, and mine
included a cloud background, but I couldn't get the colors right: a dusky
yellow cloud background. You've probably seen the hue following an afternoon
thunderstorm late spring.

I'd mix, and mix and end up with a dark yellow, that when printed over blue
turned green, or reddish or some other stupid hue. And my printmaking
professor came over, and she said to use gray, and some yellow, and some brown
(please, don't ask for the exact ink mix). When we were done, the ink sat on
the slab as a puce, but printed slightly yellow.

However, when printed over a thalo blue, it was exactly like I needed: yellow-
blue. Not green, yellow-blue. It was the damnedest thing, and not lost on the
other students: I had to remix it at least six times within a week for other
people.

The color doesn't reproduce at all on screen, so I have to assume it's
partially an optical illusion.

~~~
jrockway
_The color doesn't reproduce at all on screen, so I have to assume it's
partially an optical illusion._

I'm sure you know this, but RGB is not able to represent all possible colors,
and monitors themselves are not able to represent all of RGB. This gives us a
somewhat limited subset of available colors for use on screen, which is why (I
assume) photographs don't look as colorful as the subject did real life. The
film / CCD can't record all color information, and the print / monitor can't
display it all.

~~~
malnourish
Is there any known, or conceivable technology, that would improve the color
field for displays?

~~~
ZoFreX
There are "HDR" displays that can display a wider range of colours, my
university had one.

~~~
wtallis
HDR (high dynamic range) displays are those that can reproduce wider
differences between dark and light. What you're talking about would be called
a wide gamut display, such as an LCD with RGB LED backlighting or a special
wide-gamut fluorescent backlight.

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Natsu
When I look at the blue/yellow thing on Wikipedia, I mostly get a headache.
Depending on the angle I view it at, one color or the other dominates and it
can change colors while I'm looking at it.

I don't seem to get a blue/yellow unless you count where I can get it to be
yellow in the middle with some blue at the edges that tends to merge with the
black border.

~~~
mechanical_fish
And I find that, hilariously, my visual system actively fights the merging of
the boxes. When I successfully look at a real stereogram, there is a point at
which my eyes snap into alignment and the stereogram pops out. In this case,
it's like the opposite: I try to steer my eyes to the point where the blue and
yellow boxes overlap, but if I get close they skitter apart. It's like trying
to bring two identical magnetic poles together.

I'm sure this stuff is highly idiosyncratic. Everyone's visual system is
different. It develops via visual feedback at early ages and so is different
for everyone, sometimes to one's detriment:

<http://www.lazyeye.org/>

~~~
Groxx
It would probably help if the "+" were a more visible color than white, as it
gets lost a bit in the yellow when crossing.

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mquander
Also note imaginary colors: <http://en.wikipedia.org/wiki/Imaginary_colors>

You can see some imaginary colors here:
<http://www.skytopia.com/project/illusion/ipage-et.html>

~~~
JshWright
So... does this blue circle go away eventually? Been a few minutes and I still
can't look at a white surface without seeing a clearly defined blue circle...

~~~
Natsu
Yes, it goes away. But it may take a little while.

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sambeau
This reminded me of a fact that astounded me when I first read it: Magenta is
a colour created by our brain - there is no wavelength for it.

~~~
Someone
Color is not a physical phenomenon, but a perceptual one; there are some
wavelenghts that, in isolation, lead to perception of specific colors, but
actually, there isn't a wavelength for any color.

For example, one can have metameries
(<http://en.m.wikipedia.org/wiki/Metamerism_(color)>), where different
physiclaal signals lead to perception of the same color.

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burgerbrain
As someone who enjoys both pesto pizza, and red wine, I can safely say that
reddish-green does in fact exist.

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waqf
I once read that colour-blind synaesthetes (or color-blind synesthetes, for
you furriners) were able to perceive colours through synaesthesia that they
were physiologically incapable of perceiving with their eyes. Thus they
abnormally associated concepts with normal colours that were abnormal to them.

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mitko
They used to teach us elementary school that "blue+yellow=green". With the
advance of science we fix some of our naive illusions. I don't know how many
new we introduce...

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bane
Neon brown.

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dsc
I can't cross my eyes :(

