I didn't learn much from reading this article. Questions linger in my mind, for example: What are the CIE XYZ coordinates of each colored square? What is the spectral distribution of each square? How were the colors chosen?
The Viking Mars Lander had an early colour chart (three times over, for some reason) as shown in this NASA photo: https://www.msss.com/mars/pictures/viking_lander/22a158corr....
lol, made me chuckle.
Tip:
1. install "uBlock Origin", and configure it to "Medium Mode" [1]
2. Install "Obsidian Web Clipper" and use the "Reading View" button to read articles [2]
Trust me, you'll love it.
[1] https://github.com/gorhill/uBlock/wiki/Blocking-mode#medium-...
[2] https://addons.mozilla.org/en-US/firefox/addon/web-clipper-o...
In the most expensive versions, they measure each individual patch, in case printing imperfections make the colours slightly different. And of course because you can’t get the exact same inks when a product is 50 years old!
> How were the colors chosen?
Skin and foliage; primary colours; greyscale; and miscellaneous.
They also make a 140 colour patch version - the “ColorChecker Digital SG” - that provides more coverage; 14 different skin tones instead of 2 for example!
In the spirit of the classic “Reality Has a Surprising Amount of Detail,” [0] I realized relatively late in life how finite and how discrete the set of colored substances—pigments, dyes, inks, reflective nanostructures—is. That, for example, ultramarine means ~the same thing today as it did in the lapis mines centuries ago, and so on. Frustrated, of course, by things like impurities and degradation at the hands of time and light and medium… but nevertheless finite sets of color-reflecting substances and applications at the bottom.
In my case, it was the Forbes Pigment Collection that got me started thinking about it:
https://harvardartmuseums.org/article/pigment-collection-col...
And the strange notion of “new” colors, like YInMn Blue [1], and formulations, like Klein Blue [2] (to dwell just on ultramarine-style blues!)
…I still don’t have a firm enough handle on color in all its glorious complexity to have a real point: you’re right of course that even within tightly-controlled production processes anchored in chemical reality, things drift and it’s worth paying somebody to measure if it’s important to be right—I just thought I’d offer the notion as a Sunday morning treat, in the hope that somebody else found the rabbit hole as delightful as I did :)
[0] https://johnsalvatier.org/blog/2017/reality-has-a-surprising...
[1] paper (PDF, open access): https://www.sciencedirect.com/science/article/pii/S259004982...
blurb: https://chemistry.oregonstate.edu/chemistry-news-events/yinm...
[2] https://www.centrepompidou.fr/en/pompidou-plus/magazine/arti...