[HN Gopher] Which colors are primary?
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Which colors are primary?
Author : Michelangelo11
Score : 24 points
Date : 2025-08-06 10:06 UTC (3 days ago)
(HTM) web link (jamesgurney.substack.com)
(TXT) w3m dump (jamesgurney.substack.com)
| chowells wrote:
| No mention that both sets of primaries come from the biology of
| the average human eye, and other animals might be better served
| by other colors? Ok, yeah, that's not really relevant to the
| point the article was actually getting to, but I think it's
| important to remember. There's nothing magical about those
| colors. They effectively stimulate color receptors in our eyes
| such that our brains interpret the input in ways that can be
| combined to cover a pretty large gamut of the full range our eyes
| can perceive.
|
| But as for what the article actually does focus on, I absolutely
| agree. You can create some really striking art by restricting
| your gamut to the range you can cover with a particular set of
| pigments.
| Hobadee wrote:
| In addition to this, there will always be 2 sets of "primary"
| colors for a given eye: Additive and Subtractive.
|
| Additive primary colors are necessary when you have no light,
| and need to create color. Think a black screen, and you are
| creating colors with RGB pixels.
|
| Subtractive primary colors are necessary when you have full-
| spectrum (white) light and need to filter down to a single
| color.
|
| Other "primary" colors, such as the red, blue, yellow pigment
| primaries we learned in Kindergarten exist because pigments
| historical couldn't be created perfectly, and those "primaries"
| are the best way of getting the most colors, but still have a
| very limited (by comparison) gamut.
| kurthr wrote:
| Yes, one challenge with defining Subtractive primaries is
| that they are dependent on the white point of the "white"
| light source (e.g. D65 vs D50). While this seems
| inconvenient, it's worth noting that the apparent color of
| greys for Additive primaries is also dependent on surrounding
| illumination.
|
| So primaries are useful for generating roughly orthogonal
| changes in perceived color, but they don't tell you how they
| will be perceived in absolute terms without knowing
| surrounding illumination. In the simplest case, asking if
| something is bright (even without color) is impossible
| without knowing the surroundings.
| Diggsey wrote:
| > There will always be 2 sets of "primary" colors for a given
| eye: Additive and Subtractive.
|
| If your eye only has two types of cone cells then your
| additive and subtractive primaries are the same ;)
| gizmo686 wrote:
| I think that understanding how eyes and light work is very
| informative on this subject.
|
| Why are there 3 primary colors (regardless of which 3 you
| pick)? That has nothing to do with the nature of light, and
| everything to do with the fact that humans see light using 3
| distinct frequency response curves [0]. This means that humans
| perceive color as a 3 dimensional space; and the role of the
| primary colors is to pick a point in this space by selectively
| stimulating or masking the 3 response curves. In a world of
| pure linear algebra, almost any 3 colors would do, but physical
| reality limits how ideally we can mix them; and how much light
| they can emit/mask.
|
| Further, the 3 response curves are overlapping, so there is no
| set of ideal colors that would let you actually control the 3
| curves independently.
|
| [0] At least for color perception in a typical human.
| sdeframond wrote:
| Related: some colors can only be perceived by selectively
| hitting the right cells with tiny lasers.
|
| https://www.scientificamerican.com/article/researchers-
| disco...
| 8n4vidtmkvmk wrote:
| Put this in a VR headset, and maybe they'll finally sell?
| Ultra HDR
| morninglight wrote:
| I am surprised that the Purkinje effect and the degree of
| illumination are not mentioned. For example, should the
| primary colors be shifted depending on illumination?
|
| https://en.wikipedia.org/wiki/Purkinje_effect
| kens wrote:
| Related is that English has 11 basic color terms: black, white,
| red, green, yellow, blue, brown, orange, pink, purple, and gray.
| As a result, trying to teach cyan and magenta as primary colors
| will be much harder than teaching blue and red as primary colors.
|
| For more on basic color terms:
| https://en.wikipedia.org/wiki/Color_term#Basic_color_terms
| dehrmann wrote:
| You don't think 5-year-olds can learn two new fancy colors?
| adrian_b wrote:
| While you are right, "magenta" is just a fancy synonym for
| "purple". It might have been chosen instead of "purple" because
| the traditional word could be applied to colors having various
| proportions of red and blue, while "magenta" is intended to
| convey that the amounts of red and blue are equal. However all
| the traditional color names, like "red", "green" or "blue"
| refer to wide ranges of hues, not to a precise hue, so there
| was really no good reason for the use of the word "magenta".
|
| "Cyan" is a very bad word choice caused by confusions in the
| translations of Ancient Greek texts made by philologists
| ignorant of chemistry and mineralogy. In Ancient Greek, "cyan"
| meant pure blue, not blue-green. More precisely, it was the
| color of the ultramarine blue pigment, the most expensive blue
| pigment at that time, which was imported from the present
| territory of Afghanistan and for which the name "ku-wa-no" was
| already used by the Hittites, a millennium before the Greeks.
| Nowadays ultramarine blue is still used as a pigment, but it is
| made synthetically, so its cost is a small fraction of what it
| was before the 19th century.
|
| Before the use of "cyan" has started, the color name "blue-
| green" had been used for a very long time. Similarly, "orange"
| is a relatively new English word, but the color had been
| mentioned for many centuries, as "red-yellow" or "yellow-red".
|
| So the awareness of distinct hues is not necessarily limited to
| the set of simple color words, because most languages have used
| compound words to name the hues for which they did not have a
| simple word.
|
| Other languages have used the names of well-known colored
| objects to distinguish the hues that did not have distinct
| names. For instance, in Latin the word for "red" was used for
| both red colors and purple colors. When Latin speakers wanted
| to specify whether something was red or purple, they would say
| "red like the kermes (red) dye" or "red like the purple dye"
| (the word "purple" as a color name comes from the latter
| expression). Similarly, in Latin the word for green meant
| either green or blue-green. To distinguish the 2 colors, a
| Latin speaker would say "green like grass" or "green like
| leaves" or "green like emeralds" for expressing "green" and
| "green like the littoral sea" or "green like beryls" or "green
| like turquoise gems" for expressing "blue-green". So they were
| well aware about the differences between these colors, even if
| they did not have distinct words for them.
| LynxInLA wrote:
| You may recognize the author of this blog, he created and
| illustrated the Dinotopia series of books in the 90s.
|
| https://en.wikipedia.org/wiki/Dinotopia
| _qua wrote:
| I loved those books when I was a kid
| iambateman wrote:
| This fact blew my mind as an adult...I thought that colors were
| in fact derived from one another for my whole childhood.
|
| I don't understand why we can't teach the color wheel as a true
| wheel.
|
| But then again I recently said to a friend that "primary colors
| is just a social construct" and that didn't go so well...
| SkiFire13 wrote:
| > I don't understand why we can't teach the color wheel as a
| true wheel.
|
| Is it even a wheel though?
| dcrazy wrote:
| It's not, it's a weird loop shape:
| https://en.wikipedia.org/wiki/CIE_1931_color_space
|
| You can distort this shape into a circle but you lose the
| geometric relationship between chromaticities--two points an
| equal distance along the circumference of the color wheel
| don't necessarily feel "as different" from each other.
| Tuna-Fish wrote:
| Even this is a simplification. The color space you see is
| three-dimensional, because that is the physical reality of
| how your eyes work. Any representation of the color space
| in two dimensions involves choosing a projection that
| distorts reality.
| vladmk wrote:
| Blue and red
| hinkley wrote:
| One of the things I love about "Contact" is that the contact
| mechanism chosen by the aliens was so close to what I guessed
| aliens would use when I first learned about SETI.
|
| Decimal is not universal. Not seconds, not meters, not sound
| frequencies used for communication, not colors. Our sky isn't
| blue, it's purple. Ask any bee and they'll tell you. But hydrogen
| glows at very specific colors and that only changes if you are
| moving fast enough.
|
| The fundamental colors are the colors of the elements and, I
| might argue, their oxides. As reflected by light or when they
| incandesce. Gold. Rust. Arsenic green. Carbon black. Maybe the
| emission bands of noble gases, though those are hardly every day
| items.
|
| (If I were a very clever alien though, and I discovered exotic
| states of matter where the elements behaved differently, and I
| only wanted to talk to other very clever aliens, I might use
| those instead to talk over the heads of the younger or dumber
| species, which is why I stopped contributing to SETI. We are
| looking under the wrong rocks, IMO).
| BurningFrog wrote:
| The Aurora colors are similarly universal.
|
| The most common green color from excited nitrogen molecules
| going back to normal by emitting 557.7 nanometer photons.
| Oxygen makes 650 nm red, and the 427.8 nm blue is from nitrogen
| ions.
| esafak wrote:
| It is easier to understand additive primaries through a
| chromaticity diagram. You can form colors by mixing the
| primaries, and the gamut is determined by the hull of the
| primaries. Obviously you need at least three of them to enclose a
| space.
|
| https://commons.wikimedia.org/wiki/File:CIE1931xy_gamut_comp...
| fanf2 wrote:
| There's more to colour perception than the cone cells in the
| retina. There's also the opponent process in the visual cortex,
| which is where preschool primary colours come from.
| https://en.wikipedia.org/wiki/Opponent_process
| euroderf wrote:
| FWIW, I thought the human eye is wired for Red Yellow Green Blue
| DarkNova6 wrote:
| As somebody living in central europe I have never in my life met
| somebody who claimed that yellow is a primary color. The fact
| that this could be a thing puzzles me beyond believe.
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(page generated 2025-08-09 23:00 UTC)