

Magenta is a color - jyothi
http://arstechnica.com/science/news/2009/02/yes-virgina-there-is-a-magenta.ars

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tokenadult
This is an improvement over the earlier submitted post. Wikipedia was always
in the background

<http://en.wikipedia.org/wiki/Colour_vision>

ready to correct many of the errors in that post. "A range of wavelengths of
light stimulates each of these receptor types to varying degrees. Yellowish-
green light, for example, stimulates both L and M cones equally strongly, but
only stimulates S-cones weakly. Red light, on the other hand, stimulates L
cones much more than M cones, and S cones hardly at all; blue-green light
stimulates M cones more than L cones, and S cones a bit more strongly, and is
also the peak stimulant for rod cells; and violet light stimulates almost
exclusively S-cones. The brain combines the information from each type of
receptor to give rise to different perceptions of different wavelengths of
light." The issue is not so much one wavelength versus more than one
wavelength mixed, as it is an assignment of "color" to a combination of cone
cell responses, subject to further processing by the brain. Farther along in
the Wikipedia article it is noted,

"Chromatic adaptation

"An object may be viewed under various conditions. For example, it may be
illuminated by sunlight, the light of a fire, or a harsh electric light. In
all of these situations, human vision perceives that the object has the same
color: an apple always appears red, whether viewed at night or during the day.
On the other hand, a camera with no adjustment for light may register the
apple as having varying color."

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indiejade
Black is the only non-color. Or more precisely:

 _The combination of all colors gives white light; the absence of all color is
seen as black._ (_New York Public Library Science Desk Reference_ p. 288).

I was wondering what kind of crazy bug bit HN the other day with that "Magenta
is not a Color" bitty.

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shizcakes
Black is the only non-color when working with additive primaries (RGB, light).

Black is the presence of all colors when working with subtractive primaries
(RYB/CMYK, pigment).

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olavk
If you mix pigments of all colors you wont get black, you will probably get
some kind of brown. Thats why you need the K in CMYK - you need a specifc
black paint, which contains pigment that absorb all colors. But you cant mix
colors to get black.

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sethg
C+M+Y=K _in theory_ , but _in practice_ the pigments are not calibrated
precisely enough to be a perfect black when they combine.

~~~
olavk
I dont think that is true, even in theory. Non-black color pigments absorb
some colors but reflect other colors. So even if you mix pigments you get some
light reflected, although the color of the light will be mixed.

Just as you cannot mix black, you cannot mix white. However, a color printer
can use the white in the paper to create lighter colors.

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nostrademons
This reminds me of my philosophy class, where I learned that it is a
significant open question on what color _is_.

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soldarnal
Agreed. A statement like "The truth is, no color actually exists outside of
our brain's perception of it." flies in the face of the materialism that is so
popular these days. It sounds, rather, a great deal like George Berkeley's
idealism: _Esse est percipi._

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apag
Exactly how would it do that, pray tell?

There is zero contradiction between that statement and materialism.

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shizcakes
I'd like to point you to my comment (and its resulting thread) on the other
article: <http://news.ycombinator.com/item?id=483780>

"This article is useless. Magenta is a combination of colors, and is not
represented by any single wavelength of light. That doesn't mean it doesn't
exist. Saying magenta doesn't exist is like saying green paint doesn't exist,
because it's a combination of blue and yellow (within subtractive primaries).
[...]"

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jrockway
This is a very good article. There are way too many articles that take some
"interesting fact" and then misinterpret into something earth-shattering.
"Magenta isn't a color? HOW CAN THAT BE!?"

The original article should have said, "some colors are a single wavelength of
light, others are a combination, thanks to how your brain works." Fortunately,
this article was written to make up for the inadequacies and sensationalism in
the original.

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Tichy
Interesting, but "x" and "y" as labels for the axises on the chart made it
really hard for me to understand.

~~~
jacobolus
What would you label them instead?

[http://en.wikipedia.org/wiki/CIE_1931_color_space#The_CIE_xy...](http://en.wikipedia.org/wiki/CIE_1931_color_space#The_CIE_xy_chromaticity_diagram_and_the_CIE_xyY_color_space)

