4 ms·

Completely Painless Programmer's Guide to XYZ, RGB, ICC, XyY, and TRCs

68 points by nkurz 11y ago

jacobolus 11y ago
This description is not painless. It gets into the technical weeds before giving a good big-picture overview, which in my experience trying to teach the basics of human vision and color science usually makes people fall asleep or start walking away before they learn much. In this particular case, the technical pieces are also a very narrow and decontextualized, which as curriculum always results in severe misconceptions. This is a subject that desperately needs to be taught with many diagrams and pictures, and absolutely must begin with a basic explanation of how eyes work. Just linking to Wikipedia doesn’t cut it, as unfortunately the relevant articles on Wikipedia aren’t very good. Unfortunately there aren’t any especially good concise explanations of color science on the internet to link to. These SIGGRAPH 2001 notes are okay but leave a lot out and don’t include enough pictures: https://graphics.stanford.edu/courses/cs448b-02-spring/04cdrom.pdf https://graphics.stanford.edu/courses/cs448b-02-spring/04cdr... The best online resource I know is http://www.handprint.com/LS/CVS/color.html http://www.handprint.com/LS/CVS/color.html but it’s very long and kind of rambling. Some layman-friendly answers to various color science questions can be found at https://www.rit.edu/cos/colorscience/rc_faq_all.php https://www.rit.edu/cos/colorscience/rc_faq_all.php But really, books are better. There are a number of decent ones, e.g. http://amzn.com/047119459X http://amzn.com/047119459X or http://amzn.com/0470024259 http://amzn.com/0470024259 or http://amzn.com/1118173848 http://amzn.com/1118173848 or http://amzn.com/1568811616/ http://amzn.com/1568811616/ or the first half of http://amzn.com/1119967031 http://amzn.com/1119967031
- sago 11y ago
  I agree wholeheartedly. It goes from 'wavelength' to 'chromaticity and intensity' to 'three dimensional cartesian coordinates' without explanation. The 'color in one paragraph' paragraph would be incomprehensible if you didn't already know all the missing steps, I felt. And the need for diagrams: amen.
teddyh 11y ago
There’s always the classic “Color space FAQ”: http://www.poynton.com/ColorFAQ.html http://www.poynton.com/ColorFAQ.html
wpietri 11y ago
For the merely curious, my recommendation is that you carefully not learn about this stuff unless you need it for something. I built an automated lighting system for my house using Hue bulbs. I wanted to have more "natural" light throughout the day. Ignoring a warning from a friend ("It's as bad as knowing about kerning," he said), I learned a fair bit about color, including the very mutable and slippery concept of "white". I like my automated lighting system just fine, but the downside is that I now notice color temperature of lightbulbs. It's as annoying; things that were previously fine are now the sources of enduring irritation. So now I'm the apparently crazy person at work who unscrews lightbulbs and moves them around my work area because somebody has randomly scattered very-warm-white and very-cool-white bulbs around the place with no attention to aesthetics or utility. I was honestly happier not knowing. There are some things you can't unsee, and color temperature is one of them. I'm glad I could stop before I understood how bad the color representation is on my various screens.
- revelation 11y ago
  You should try f.lux [1], it will drive you up a wall. [1]: https://justgetflux.com/ https://justgetflux.com/
  - versteegen 11y ago
    Redshift does the same thing (supports Windows and X11), no idea what the difference is. Apparently at the time redshift was created 6 years ago f.lux didn't work properly on GNU/Linux. http://jonls.dk/redshift/ http://jonls.dk/redshift/
    - dmm 11y ago
      Redshift is free (libre) software and fl.ux is "patent pending".
  - wpietri 11y ago
    Heh. I'm actually a happy Redshift user on my laptops; ditto Twilight on my Android devices. I suppose because I'm more obsessive about good sleep than screen color representation. Indeed, my automated lighting system is basically f.lux for one's house: https://github.com/wpietri/sunrise https://github.com/wpietri/sunrise
TazeTSchnitzel 11y ago
Relatedly: HSL and HSV's concept of brightness does not match that of the human eye. HSL blue at 0.5 lightness is darker than HSL red at 0.5
deleted 11y ago
[deleted]
IgorPartola 11y ago
Well, now I need to recalibrate my monitors, except this time I will know what I am doing. Thanks for the great article.

68 points by nkurz 11y ago

This description is not painless. It gets into the technical weeds before giving a good big-picture overview, which in my experience trying to teach the basics of human vision and color science usually makes people fall asleep or start walking away before they learn much. In this particular case, the technical pieces are also a very narrow and decontextualized, which as curriculum always results in severe misconceptions. This is a subject that desperately needs to be taught with many diagrams and pictures, and absolutely must begin with a basic explanation of how eyes work. Just linking to Wikipedia doesn’t cut it, as unfortunately the relevant articles on Wikipedia aren’t very good. Unfortunately there aren’t any especially good concise explanations of color science on the internet to link to. These SIGGRAPH 2001 notes are okay but leave a lot out and don’t include enough pictures: https://graphics.stanford.edu/courses/cs448b-02-spring/04cdrom.pdf https://graphics.stanford.edu/courses/cs448b-02-spring/04cdr... The best online resource I know is http://www.handprint.com/LS/CVS/color.html http://www.handprint.com/LS/CVS/color.html but it’s very long and kind of rambling. Some layman-friendly answers to various color science questions can be found at https://www.rit.edu/cos/colorscience/rc_faq_all.php https://www.rit.edu/cos/colorscience/rc_faq_all.php But really, books are better. There are a number of decent ones, e.g. http://amzn.com/047119459X http://amzn.com/047119459X or http://amzn.com/0470024259 http://amzn.com/0470024259 or http://amzn.com/1118173848 http://amzn.com/1118173848 or http://amzn.com/1568811616/ http://amzn.com/1568811616/ or the first half of http://amzn.com/1119967031 http://amzn.com/1119967031

sago 11y ago
I agree wholeheartedly. It goes from 'wavelength' to 'chromaticity and intensity' to 'three dimensional cartesian coordinates' without explanation. The 'color in one paragraph' paragraph would be incomprehensible if you didn't already know all the missing steps, I felt. And the need for diagrams: amen.

teddyh 11y ago

There’s always the classic “Color space FAQ”: http://www.poynton.com/ColorFAQ.html http://www.poynton.com/ColorFAQ.html

wpietri 11y ago

For the merely curious, my recommendation is that you carefully not learn about this stuff unless you need it for something. I built an automated lighting system for my house using Hue bulbs. I wanted to have more "natural" light throughout the day. Ignoring a warning from a friend ("It's as bad as knowing about kerning," he said), I learned a fair bit about color, including the very mutable and slippery concept of "white". I like my automated lighting system just fine, but the downside is that I now notice color temperature of lightbulbs. It's as annoying; things that were previously fine are now the sources of enduring irritation. So now I'm the apparently crazy person at work who unscrews lightbulbs and moves them around my work area because somebody has randomly scattered very-warm-white and very-cool-white bulbs around the place with no attention to aesthetics or utility. I was honestly happier not knowing. There are some things you can't unsee, and color temperature is one of them. I'm glad I could stop before I understood how bad the color representation is on my various screens.

revelation 11y ago
You should try f.lux [1], it will drive you up a wall. [1]: https://justgetflux.com/ https://justgetflux.com/
- versteegen 11y ago
  Redshift does the same thing (supports Windows and X11), no idea what the difference is. Apparently at the time redshift was created 6 years ago f.lux didn't work properly on GNU/Linux. http://jonls.dk/redshift/ http://jonls.dk/redshift/
  - dmm 11y ago
    Redshift is free (libre) software and fl.ux is "patent pending".
- wpietri 11y ago
  Heh. I'm actually a happy Redshift user on my laptops; ditto Twilight on my Android devices. I suppose because I'm more obsessive about good sleep than screen color representation. Indeed, my automated lighting system is basically f.lux for one's house: https://github.com/wpietri/sunrise https://github.com/wpietri/sunrise

TazeTSchnitzel 11y ago

Relatedly: HSL and HSV's concept of brightness does not match that of the human eye. HSL blue at 0.5 lightness is darker than HSL red at 0.5

deleted 11y ago

[deleted]

IgorPartola 11y ago

Well, now I need to recalibrate my monitors, except this time I will know what I am doing. Thanks for the great article.