
Color and Reality - rms
http://www.gmilburn.ca/2009/06/19/color-and-reality/
======
seldo
My own version of this childhood theory was that everyone has the same
favourite colour, but our brains saw it on different parts of the spectrum. So
my favourite colour is what I call blue, and you see the same colour when you
look at green.

~~~
leif
I think having this thought is one of the fundamentally human experiences, as
every time I talk to someone about this idea, they tell me that they, too, had
it at an early age.

Thank you for confirming the ultimate weirdness of the universe for me.

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RISCfuture
This problem is studied deeply in the philosophy of color, and there are three
major theories on the relationship between light, color, and experience:

The theory of physicalism states that an object's color is an intrinsic
property of matter, that its color is determined by its atomic properties.
This theory is largely discredited in modern philosophy.

The theory of relationalism states that an object's color is determined by the
atomic properties of the object in combination with physical properties of the
environment: ambient light, reflection/refraction, diffusion, etc.

The theory of projectivism states that an object's color is a combination of
its physical properties and the perception in the viewer; namely, that color
is an experience tied to a dual system of subject and perceiver. This is the
generally accepted theory today.

There's a large body of work on the philosophy of color (most of it sitting in
my girlfriend's bookshelf). See <http://plato.stanford.edu/entries/color/> for
an example of the depth of the topic.

~~~
jacobolus
Fortunately we have neuroscience to discredit the first two theories.

~~~
jerf
Following up on your comment, it can be more-or-less _proved_ that human color
is a neural construction based on light input by looking at things like
optical illusions, such as this classic white-lines-and-black-boxes affair:
<http://www.michaelbach.de/ot/lum_herGrid/index.html>

You might think this isn't a color demonstration, but it is actually a
compelling example that beyond just the spectrum of the photons hitting your
eye, the brain is doing a lot of additional work involving what we call
"colors". Further evidence: The broad similarities between what attributes
cultures ascribe to colors. Yes, there are differences too, but there's a lot
of correlations there, added by your brain, which comes preprogrammed with
some meaning-ish things. (It's not that direct, but since I'm working in
English here that sentence will have to do.) We know we share similar "red"
and "green" experiences because we share their clashing effect. I'm not sure
if there's anybody who has ever moved from not-red-green-colorblind to red-
green-colorblind, but in a real sense, a red-green colorblind person is seeing
a different color, with different properties and different aesthetics. Their
aesthetics aren't wrong, just different.

(Related: It is frequently complained that aliens on TV are just humans with a
bit of latex stuck to them, but there are numerous other ways in which aliens
are just "humans with bits stuck on", and one of the most notable is how many
alien civilizations basically _look good_ on TV. I'm willing to buy that an
alien race building a real engineering artifact will build something with a
_form_ that appeals to us, just as many aliens-on-earth do (spiders, for
instance), but their colors ought to be alternatively garish beyond belief,
subdued beyond our ability to recognize (10 million shades of blue and
combinations of blue), or just plain random (a gamut twice ours, perhaps, or a
race with no equivalent to vision at all, though I find that one hard to
swallow), as they work with colors that may happen to share the same
wavelengths of light (or not) but otherwise have nothing in common with human
colors.)

In other interesting thoughts, when we can directly stimulate the human optic
nerve, I look forward to the seeing what happens when we move out of the CIE
color space. IIRC, the boundaries of the CIE color space represent the point
where the three color receptors in the eye would need a negative photon to
generate that result, which can't exist in real life. This implies to me that
such values _could_ be generated by direct stimulation, though. Are there
colors that no human has ever seen, but nearly every human is equipped to
experience in much the same way as any other color, in some sense as much a
color as any of the ones we know? Perhaps some of us will even find out, some
day.

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teilo
It would be helpful if he used Cyan for Turquoise and Magenta for Pink, since
those are the accepted terms when speaking of color primaries.

Also, there is a difference between how one sees color and how well one is
able to distinguish one color from another.

The CIE color model was based upon, if memory serves, testing done on 25 white
french males, about the worst possible test group so far as color acuity is
concerned. They should have chosen asian women, who have the highest color
acuity as a population, that is, the ability to distinguish shades from one
another.

~~~
jacobolus
Since “primary” is a cultural rather than perceptual designation, and since
both the particular colors chosen to express his ideas (that is, infinitely
many choices of purples could be made which would still be extra-spectral),
and the labels he uses, are arbitrary, I don’t see how it matters.

What does this mean? Color is a perceptual quality, not a physical one, so the
ability to distinguish colors is intimately tied to their definition.

Since most people have fairly similar cone spectral responses, basing the
model on an Asian woman instead of a French man wouldn’t really change it
much. If using CIE colorimetry didn’t work pretty well, we wouldn’t still be
using it all these decades later.

~~~
teilo
"Primary" is not a cultural designation. Cyan, Magenta, and Yellow are the
subtractive primaries which correspond exactly to the Red, Green, and Blue
additive primaries. This isn't culture. It's science.

And CIE colorimetry works, but I can tell you from experience, it does not
work "very well". Rather it is adequate given the DeltaE tolerance of any
given project. That is why the world is moving to spectrographic models, and
there are already alternatives in the works which stand to replace
CIE/LAB/XYZ, for precisely the reason that they have proved inadequate to the
task of modern color management.

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greendestiny
I think any discussion of colour without mentioning the sensitivity curves of
Cone cells is pretty incomplete. We don't somehow have perfect knowledge of
the frequency of individual photons and build up 'imaginary' colours from
that, we just map activation levels from our 3 (usually) types of Cone cells
to a continuous space.

~~~
klipt
Another way to look at it is that colour is effectively an infinite
dimensional vector, but we can only sense a 3 dimensional function of that.
(Fewer dimensions if you're colourblind, more if you're a bird.)

~~~
jacobolus
Wrong. _Light spectra_ are infinite-dimensional. But _color_ is a neural
response to stimulus: it is definitionally identical to what we can sense.

------
known
Is your system ICC Version 4 ready? <http://www.color.org/version4html.xalter>

~~~
amvp
Windows firefox users can enable colour management in about:config by setting
gfx.color_management.enabled to true. It's my understanding that safari is one
of the few browsers on windows that gets it right out of the box.

