6 ms·

I've had a dream project for years, but I have no idea how to do it. To build an accurate physical representation of the CIE 1931 xy plane. To see literally all

I've had a dream project for years, but I have no idea how to do it. To build an accurate physical representation of the CIE 1931 xy plane. To see literally all the colors before your eyes at once. To see how far into infrared and ultraviolet your perception extends. Looking at an RGB rendering of CIE 1931 is kinda sad and makes me wonder of all the colors I've never seen.

devwastaken 6y ago
The problem with that is probably color accuracy. Usually with things like UV light sources you have to have a specific filter glass that blocks out most of the visible light being emitted. Perhaps you need to somehow create a rapidly changing filter glass of all different wavelengths. Purely hypothetical.
- formerly_proven 6y ago
  > Perhaps you need to somehow create a rapidly changing filter glass of all different wavelengths. Purely hypothetical. Monochromatic colors are just a tiny, tiny sliver of the perceptible color space. They're not even the boundary of it, they're such a small part of perception that they're only a part of the boundary. In the CIE model, the curved part of the boundary represents monochromatic colors. The surface itself is not monochromatic, and neither is the straight boundary (line of purples). And that model is a simplification in and of itself.
weinzierl 6y ago
I've had the same dream for years until I realized that the reason I had no idea how to do it is actually that it is impossible. Of course approximations are possible and they do exist, but to make such a diagram accurate and comprehensive at the same time there are multiple obstacles: First of all the obvious fact that there is no printing or display technique with an all encompassing gamut. Also CIE 1931 is not perceptually uniform and unsuitable "To see how far [..] your perception extends.", as you expressed it. Apart from the technical difficulties the problems run deeper: Color space in reality is non-Euclidian. There is not even a perceptually uniform embedding in 3D Euclidian space, let alone one in 2D. This is how jacobolus put it once: "No, it’s not possible to have uniform color differences at all scales and in all directions in a 3-dimensional Euclidean space. If you go around a hue circle in little steps and then sum up all the perceived color differences you end up with more than π times the sum of differences you get if you go across the circle through gray." [1] Unfortunately your diagram can either be a fairly accurate depiction of a part or a fairly inaccurate depiction of the whole. [1] https://news.ycombinator.com/item?id=15485397 https://news.ycombinator.com/item?id=15485397
- fouronnes3 6y ago
  All good points. Thanks for that answer! Maybe it's possible to make a device that shows a single point of the color perception space of the human eye, but could show all the points? I'm thinking lots of monochromatic sources and optical mixing. The you could at least pick a point at a time of CIE 1931 and look at it.
user-the-name 6y ago
CIE 1931 does not actually represent any deeper reality. It does not contain "literally all colours", it is a highly simplified mathematical model of colour, with plenty of tradeoffs and issues. It does not contain ultraviolet or infrared, those are entirely outside its scope.
OscarCunningham 6y ago
> To see how far into infrared and ultraviolet your perception extends. For this one you could use a prism with a full-spectrum light behind it.

devwastaken 6y ago

The problem with that is probably color accuracy. Usually with things like UV light sources you have to have a specific filter glass that blocks out most of the visible light being emitted. Perhaps you need to somehow create a rapidly changing filter glass of all different wavelengths. Purely hypothetical.

formerly_proven 6y ago
> Perhaps you need to somehow create a rapidly changing filter glass of all different wavelengths. Purely hypothetical. Monochromatic colors are just a tiny, tiny sliver of the perceptible color space. They're not even the boundary of it, they're such a small part of perception that they're only a part of the boundary. In the CIE model, the curved part of the boundary represents monochromatic colors. The surface itself is not monochromatic, and neither is the straight boundary (line of purples). And that model is a simplification in and of itself.

weinzierl 6y ago

I've had the same dream for years until I realized that the reason I had no idea how to do it is actually that it is impossible. Of course approximations are possible and they do exist, but to make such a diagram accurate and comprehensive at the same time there are multiple obstacles: First of all the obvious fact that there is no printing or display technique with an all encompassing gamut. Also CIE 1931 is not perceptually uniform and unsuitable "To see how far [..] your perception extends.", as you expressed it. Apart from the technical difficulties the problems run deeper: Color space in reality is non-Euclidian. There is not even a perceptually uniform embedding in 3D Euclidian space, let alone one in 2D. This is how jacobolus put it once: "No, it’s not possible to have uniform color differences at all scales and in all directions in a 3-dimensional Euclidean space. If you go around a hue circle in little steps and then sum up all the perceived color differences you end up with more than π times the sum of differences you get if you go across the circle through gray." [1] Unfortunately your diagram can either be a fairly accurate depiction of a part or a fairly inaccurate depiction of the whole. [1] https://news.ycombinator.com/item?id=15485397 https://news.ycombinator.com/item?id=15485397

fouronnes3 6y ago
All good points. Thanks for that answer! Maybe it's possible to make a device that shows a single point of the color perception space of the human eye, but could show all the points? I'm thinking lots of monochromatic sources and optical mixing. The you could at least pick a point at a time of CIE 1931 and look at it.

user-the-name 6y ago

CIE 1931 does not actually represent any deeper reality. It does not contain "literally all colours", it is a highly simplified mathematical model of colour, with plenty of tradeoffs and issues. It does not contain ultraviolet or infrared, those are entirely outside its scope.

OscarCunningham 6y ago

> To see how far into infrared and ultraviolet your perception extends. For this one you could use a prism with a full-spectrum light behind it.