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Like many resources about color, this one has an output-medium-centric followed by early-20th-century-experiment-design-centric viewpoint, presumably because th

Like many resources about color, this one has an output-medium-centric followed by early-20th-century-experiment-design-centric viewpoint, presumably because that was where the author started and what he read about. But however perfect the exposition might otherwise be, that is the wrong way to start a general discussion of the subject, and the result is inevitably misleading and confusing for non-experts. > it is a pragmatic approach Having tried to talk face-to-face to many people from different backgrounds about color, in practice this doesn’t work. People are starting with too many misconceptions and gaps in foundational knowledge. If you want to understand color you have to start with at least the basics about the physiology of human vision, along with some basic optics. It is all but impossible to properly understand what is going on with RGB displays, understand what “white point” means, etc. without that background. One of the resource recommended at the end, Bruce MacEvoy’s site http://handprint.com/LS/CVS/color.html http://handprint.com/LS/CVS/color.html is a much better starting place, albeit pretty long for someone just interested in the basics. Or there are many books about human color vision and color reproduction, some friendlier for laypeople and others highly detailed and technical. To understand recent color models Mark Fairchild’s book Color Appearance Models is pretty good, and the first half is a pretty accessible general overview. Or for more about color reproduction try Billmeyer and Saltzman’s Principles of Color Technology (recent editions rewritten by Roy Berns). For more about colorimetry try Hunt & Pointer’s book Measuring Color. Or for something historical, try Kuehni’s Color Space and Its Divisions.

cmurf 8y ago
There are quite a few legitimate entry points. There's a huge body of artists who had no idea about the physiology of human vision but absolutely understood hue, chroma, brightness. They clearly understood the real world was HDR even if they didn't use that term. They understood the massive loss of dynamic range of their artwork, and yet they developed the concept of rendering in order to compress shadow and highlight detail to preserve some sense of the real world when important and to clip it when it wasn't important. And you don't even have to go back 600 years for such examples, even today's amateur photographer learns about these problems and work arounds, without the benefit of learning any physiology. We can't all dedicate the time to read Wyszecki and Stiles as the entry point into color and imaging, albeit of course it's quite useful for those who need to understand such origin stories and the math for all of it.
- jacobolus 8y ago
  Yes, you can develop a good intuitive understanding if you spend 15 years or whatever painting full time (the first several years mostly bumbling around under various misconceptions making lots of mistakes) as an alternative to reading a few pages about how the eye works, if you prefer. In painting (or, say, in developing dye transfer prints in a darkroom) having a deep understanding of the output medium is essential to do any kind of passable work, because color mixtures need to be made quite explicitly by the artist. The artist can’t just pluck a 10 YR 8/10 chip out of their Munsell Book of Color and immediately transfer the color to their canvas. Instead they have to squeeze some particular paints out of tubes and smear them together with a brush. But even so, it is very helpful for painters, graphic designers, photographers, darkroom photo printers, etc. to learn a bit about how color vision and optics work. It will help organize and clarify their intuition, help them have comprehensible conversations with other artists or laypeople, help them transfer skills between media, and so on. It’s deeply unfortunate that new computer artists are subjected to RGB values just because highly experienced painters can learn to work with a similar system. More perceptually relevant models are much nicer to work with in user interfaces.
slavik81 8y ago
The article is very well written, but the order does feel a little backwards to me too. Color spaces are confusing because they are not physical things. They're abstractions created by people to solve problems. You can come to understand a solution without understanding the problem, but I definitely think it's the harder way to approach learning. There's a 10 minute overview of color theory from "A better default colormap for Matplotlib" that I really like. It's very condensed, but it takes you from light, to perception, to color spaces: https://youtu.be/xAoljeRJ3lU?t=218 https://youtu.be/xAoljeRJ3lU?t=218
mncharity 8y ago
> People are starting with too many misconceptions and gaps in foundational knowledge. [...] start with at least the basics about the physiology of human vision A question I ask first-tier physical-sciences graduate students is "A five-year old comes up to you and asks, 'I'm told the Sun is a big hot ball. Awesome! What color is the ball? I really care about the color of balls - I'm 5.' What color is the Sun?". Among the pervasively incorrect answers I get, is a recurrent "It doesn't have a color; it's lots of different colors; it's rainbow color." It reminds me of a failure mode in learning high-school stoichiometry: students not thinking of atoms as real physical objects. And why should letters be conserved?
- jacobolus 8y ago
  For a 5-year-old I might say something like: “The sun is so bright when it is high in the sky that it will permanently wreck your vision – please don’t look directly at the sun! – so it’s hard to give it a color label, but let’s say it looks ‘white’. Notice that the sky absorbs some of the light coming from the sun to us, changing the apparent color depending on how much sky we are looking through, so when the sun is very close to the horizon and we are looking through a whole lot of sky to see it, it looks orange. In between it looks like various yellows.” Coming up with well-defined named color categories that will work for both surface colors and an emissive source as bright as the sun is hard to begin with. Talking about color in a precise way with 5-year-olds is even tougher.
  - mncharity 8y ago
    I'd tweak that as... "The ball is white." So often in education, the most significant bit is neglected. For example, atoms are tiny little balls, sticky little balls that jiggle (insanely fast)... and yet, not thinking of them as real physical objects, something you can teach pre-K, is a failure mode teaching stoichiometry in high-school, and in some intro college chemistry. NASA has done entire museum exhibits about the Sun, bereft of a single ball, or a single true-color image. Imagine a museum exhibit about elephants, without a single model, and only false-color images. Images of elephant surface temperature, of skin parasite density, of average mud thickness, etc. But not a single gray elephant in the room. Would you not then be, "WTF were they thinking?"? I'd skip the distinction between "really is white" vs "appears white because eye has been saturated by brightness, or is monochrome from dimness". And also the issue of color accommodation. Because the Sun really is white. As can be demoed by sunlight through a gap (window, leaves, pinhole camera) on a white surface, or through a neutral filter. I like the emphasis on media. "The white ball... (Not) seen from underground, or from a closet, or from deep in the ocean, appears black. :) Seen from underwater, through tens of meters of water, appears blueish. Seen from under the atmosphere, low in the sky through lots of atmosphere, appears redish. Seen higher in the sky through not much atmosphere, appears white." Years ago I saw a NATO full-sky survey, which had Sun chromaticity as white, even through clouds, until quite low in the sky (in rural Spain I think?, so not much dust or smog). I wish I could be more specific with that "redish" and "atmosphere", but I've not seen real data. If one wants to clearly and correctly explain something to a 5-year old... expect to spend a lot of time with scihub. > Coming up with well-defined named color categories that will work for both surface colors and an emissive source as bright as the sun is hard to begin with. Talking about color in a precise way with 5-year-olds is even tougher. Might this be a misunderstanding of color? Light has a spectrum, and thus a color, regardless of where the light came from. And can be so bright as to appear to the eye white, or so dim as to appear dark gray (rods vs cones), also regardless. > Talking about color in a precise way with 5-year-olds is even tougher. Here's a fun cautionary tale. There's a genre of science education research ph.d theses that basically goes "We tried to teach science topic X to grade G. <Implict: We didn't really understand the subject, and taught it the-usual badly, often facepalm shockingly badly.> We were surprised and disappointed that this didn't work. We draw the obvious conclusion... Students in grade G are developmentally incapable of understanding topic X." :) I've come to think of "you can't explain <subject> to <age>" as analogous to a code smell. Drifting off topic, but a random thought... if you watch even best-practices classroom video, say around estimation, it often seems like the teacher is coaching students on how to pretend to understand the material. Pretend well enough for the teacher to nod and move on. So for instance, the use of an only-locally-equivalent alternative to actually understanding will be encouraged, not debugged. So perhaps there's a mismatch between a nominal goal of "learn science", and an actual goal of "learn to pretend to have learned science". And one might get better results by abandoning one or the other, in favor of consistency and transparency. Random thought. Thanks for the comment!
pasta 8y ago
It's also important to understand that color spaces are used for medium to medium conversions. Human perception is always a part of this but not always the goal. For example in print a color space can be used to control how ink flows on paper. A lot of ink for dark colors on thin paper will result in a mess. That's why a color space converted image for such a print will look waay to light. But the result will be a good dark print. And ofcourse this looks much better to the human eye. Edit: I might be confusing the term color profile...
Exuma 8y ago
Hijacking this comment to ask a question... so is this guide saying that regular RGB at 100% intensity (no transformation) cannot represent every single color? This is a bit confusing to me, as I thought it could. I was always under the impression that RGB values could represent all colors that can be represented on a monitor
- deleted 8y ago
  [deleted]
- jacobolus 8y ago
  Yes, often the gamut for a computer display and the gamut of a particular working color space (like sRGB) intersect each-other, with some colors in each gamut which are outside the other. If you use a linear representation of RGB coordinates, and allow values less than 0 or greater than 1, then you can represent any conceivable color. But most image formats do not support values outside the [0, 1] range. If you have an image in one color space, and you want to convert it to another color space (e.g. for showing on your display or printing) there are many possible gamut mapping algorithms you might use to optimize the results according to various criteria. Here is a 300 page book about some of the possibilities, https://www.wiley.com/en-us/Color+Gamut+Mapping-p-9780470030325 https://www.wiley.com/en-us/Color+Gamut+Mapping-p-9780470030...
  - Exuma 8y ago
    Good lord that is a large technical book about one topic O_O

cmurf 8y ago

There are quite a few legitimate entry points. There's a huge body of artists who had no idea about the physiology of human vision but absolutely understood hue, chroma, brightness. They clearly understood the real world was HDR even if they didn't use that term. They understood the massive loss of dynamic range of their artwork, and yet they developed the concept of rendering in order to compress shadow and highlight detail to preserve some sense of the real world when important and to clip it when it wasn't important. And you don't even have to go back 600 years for such examples, even today's amateur photographer learns about these problems and work arounds, without the benefit of learning any physiology. We can't all dedicate the time to read Wyszecki and Stiles as the entry point into color and imaging, albeit of course it's quite useful for those who need to understand such origin stories and the math for all of it.

jacobolus 8y ago
Yes, you can develop a good intuitive understanding if you spend 15 years or whatever painting full time (the first several years mostly bumbling around under various misconceptions making lots of mistakes) as an alternative to reading a few pages about how the eye works, if you prefer. In painting (or, say, in developing dye transfer prints in a darkroom) having a deep understanding of the output medium is essential to do any kind of passable work, because color mixtures need to be made quite explicitly by the artist. The artist can’t just pluck a 10 YR 8/10 chip out of their Munsell Book of Color and immediately transfer the color to their canvas. Instead they have to squeeze some particular paints out of tubes and smear them together with a brush. But even so, it is very helpful for painters, graphic designers, photographers, darkroom photo printers, etc. to learn a bit about how color vision and optics work. It will help organize and clarify their intuition, help them have comprehensible conversations with other artists or laypeople, help them transfer skills between media, and so on. It’s deeply unfortunate that new computer artists are subjected to RGB values just because highly experienced painters can learn to work with a similar system. More perceptually relevant models are much nicer to work with in user interfaces.

slavik81 8y ago

The article is very well written, but the order does feel a little backwards to me too. Color spaces are confusing because they are not physical things. They're abstractions created by people to solve problems. You can come to understand a solution without understanding the problem, but I definitely think it's the harder way to approach learning. There's a 10 minute overview of color theory from "A better default colormap for Matplotlib" that I really like. It's very condensed, but it takes you from light, to perception, to color spaces: https://youtu.be/xAoljeRJ3lU?t=218 https://youtu.be/xAoljeRJ3lU?t=218

mncharity 8y ago

> People are starting with too many misconceptions and gaps in foundational knowledge. [...] start with at least the basics about the physiology of human vision A question I ask first-tier physical-sciences graduate students is "A five-year old comes up to you and asks, 'I'm told the Sun is a big hot ball. Awesome! What color is the ball? I really care about the color of balls - I'm 5.' What color is the Sun?". Among the pervasively incorrect answers I get, is a recurrent "It doesn't have a color; it's lots of different colors; it's rainbow color." It reminds me of a failure mode in learning high-school stoichiometry: students not thinking of atoms as real physical objects. And why should letters be conserved?

jacobolus 8y ago
For a 5-year-old I might say something like: “The sun is so bright when it is high in the sky that it will permanently wreck your vision – please don’t look directly at the sun! – so it’s hard to give it a color label, but let’s say it looks ‘white’. Notice that the sky absorbs some of the light coming from the sun to us, changing the apparent color depending on how much sky we are looking through, so when the sun is very close to the horizon and we are looking through a whole lot of sky to see it, it looks orange. In between it looks like various yellows.” Coming up with well-defined named color categories that will work for both surface colors and an emissive source as bright as the sun is hard to begin with. Talking about color in a precise way with 5-year-olds is even tougher.
- mncharity 8y ago
  I'd tweak that as... "The ball is white." So often in education, the most significant bit is neglected. For example, atoms are tiny little balls, sticky little balls that jiggle (insanely fast)... and yet, not thinking of them as real physical objects, something you can teach pre-K, is a failure mode teaching stoichiometry in high-school, and in some intro college chemistry. NASA has done entire museum exhibits about the Sun, bereft of a single ball, or a single true-color image. Imagine a museum exhibit about elephants, without a single model, and only false-color images. Images of elephant surface temperature, of skin parasite density, of average mud thickness, etc. But not a single gray elephant in the room. Would you not then be, "WTF were they thinking?"? I'd skip the distinction between "really is white" vs "appears white because eye has been saturated by brightness, or is monochrome from dimness". And also the issue of color accommodation. Because the Sun really is white. As can be demoed by sunlight through a gap (window, leaves, pinhole camera) on a white surface, or through a neutral filter. I like the emphasis on media. "The white ball... (Not) seen from underground, or from a closet, or from deep in the ocean, appears black. :) Seen from underwater, through tens of meters of water, appears blueish. Seen from under the atmosphere, low in the sky through lots of atmosphere, appears redish. Seen higher in the sky through not much atmosphere, appears white." Years ago I saw a NATO full-sky survey, which had Sun chromaticity as white, even through clouds, until quite low in the sky (in rural Spain I think?, so not much dust or smog). I wish I could be more specific with that "redish" and "atmosphere", but I've not seen real data. If one wants to clearly and correctly explain something to a 5-year old... expect to spend a lot of time with scihub. > Coming up with well-defined named color categories that will work for both surface colors and an emissive source as bright as the sun is hard to begin with. Talking about color in a precise way with 5-year-olds is even tougher. Might this be a misunderstanding of color? Light has a spectrum, and thus a color, regardless of where the light came from. And can be so bright as to appear to the eye white, or so dim as to appear dark gray (rods vs cones), also regardless. > Talking about color in a precise way with 5-year-olds is even tougher. Here's a fun cautionary tale. There's a genre of science education research ph.d theses that basically goes "We tried to teach science topic X to grade G. <Implict: We didn't really understand the subject, and taught it the-usual badly, often facepalm shockingly badly.> We were surprised and disappointed that this didn't work. We draw the obvious conclusion... Students in grade G are developmentally incapable of understanding topic X." :) I've come to think of "you can't explain <subject> to <age>" as analogous to a code smell. Drifting off topic, but a random thought... if you watch even best-practices classroom video, say around estimation, it often seems like the teacher is coaching students on how to pretend to understand the material. Pretend well enough for the teacher to nod and move on. So for instance, the use of an only-locally-equivalent alternative to actually understanding will be encouraged, not debugged. So perhaps there's a mismatch between a nominal goal of "learn science", and an actual goal of "learn to pretend to have learned science". And one might get better results by abandoning one or the other, in favor of consistency and transparency. Random thought. Thanks for the comment!

pasta 8y ago

It's also important to understand that color spaces are used for medium to medium conversions. Human perception is always a part of this but not always the goal. For example in print a color space can be used to control how ink flows on paper. A lot of ink for dark colors on thin paper will result in a mess. That's why a color space converted image for such a print will look waay to light. But the result will be a good dark print. And ofcourse this looks much better to the human eye. Edit: I might be confusing the term color profile...

Exuma 8y ago

Hijacking this comment to ask a question... so is this guide saying that regular RGB at 100% intensity (no transformation) cannot represent every single color? This is a bit confusing to me, as I thought it could. I was always under the impression that RGB values could represent all colors that can be represented on a monitor

deleted 8y ago
[deleted]
jacobolus 8y ago
Yes, often the gamut for a computer display and the gamut of a particular working color space (like sRGB) intersect each-other, with some colors in each gamut which are outside the other. If you use a linear representation of RGB coordinates, and allow values less than 0 or greater than 1, then you can represent any conceivable color. But most image formats do not support values outside the [0, 1] range. If you have an image in one color space, and you want to convert it to another color space (e.g. for showing on your display or printing) there are many possible gamut mapping algorithms you might use to optimize the results according to various criteria. Here is a 300 page book about some of the possibilities, https://www.wiley.com/en-us/Color+Gamut+Mapping-p-9780470030325 https://www.wiley.com/en-us/Color+Gamut+Mapping-p-9780470030...
- Exuma 8y ago
  Good lord that is a large technical book about one topic O_O