4

(I hope this is the correct site to ask this; if it isn't, sincere apologies ─ and please help me find a good place to ask :-).)

I'm a physicist and I've been dabbling in color theory for some time, partly to ensure that my use of color in scientific publications is as accurate as possible (example), and partly because I find human color vision an interesting subject in its own right.

One of the aspects that I find rather frustrating is the fact that many resources that describe color spaces talk about colors that do not fall inside the RGB triangles that my digital devices' screens can display, which means that when e.g. I see a plot describing the types of colors that the Adobe or ProPhoto RGB standards can render,

Image source; Image source.

the important parts of the plot are basically left to the imagination, as the device I'm using to display the plot is intrinsically unable to display the colors that the plot is trying to talk about.

I would like a physical resource that's able to overcome this limitation - something like a physical printout of the chromaticity plot above, or an equivalent cutout through 3D color space, which does have the colors that my monitor cannot show me. I tried looking for this but I couldn't find it, and I can't figure out whether that's because it's not something that's actually sold (in which case: why?) or whether I'm just not using the correct search terms. I'm mostly looking for a casual print rather than full professional standard (i.e. if the price gets driven by an accuracy guarantee, then it'll likely be too much), but even if professional standards are the only ones available I'd like to know what they are and how to find them.

Since you guys are in daily contact with color, and with the interfaces between digital, screen, print, and real-world color, I was hoping that you could point me in the right direction.

  • 2
    One of the problems is you'll run into a similar issue - printers that can print every color across an entire color space are pretty rare, if they exist at all. In addition, the portion of a color space that a printer can cover will rarely if ever correspond to the portion that can be covered by a monitor - there'll be a lot of overlap, but there'll generally be some portions covered by either device that aren't covered by the other. This is what color management is all about. – twalberg Aug 31 '18 at 15:33
  • 1
    I'm voting to close this question as off-topic because it is not concerned with solving a problem related to actually taking photographs. – Michael C Aug 31 '18 at 18:22
  • 1
    @MichaelClark A shift in color appearance on one print due to change in illuminant is not metameric failure. A shift in color between two things with different spectral reflectances that look the same under one illuminant but different when viewed under another illuminant is metameric failure. A print does not exhibit this since any one printed color has a specific spectral reflectance. However, prints made with different inks on a different printer can. A color on one can match that of the other under one illuminant but not a different illuminant. – doug Aug 31 '18 at 18:48
  • 1
    a good and interesting question...but probably off-topic here – osullic Aug 31 '18 at 19:07
  • 1
    @MichaelClark Different combinations of pigments that produce the same color under one illuminant but not another is metameric failure. That can occur when viewing the same color on prints from different printers but not on a singular print since any one color on one print is produced from a specific combination of inks and has a specific spectrum. While theoretically a printer could print the same color in two locations with different inks this isn't possible normally as each color defines a inking recipe. – doug Aug 31 '18 at 19:19
6

It simply isn't possible for any print, which only absorbs light, to produce a colorimetrically accurate and useful reproduction of the CIEXY human gamut "horseshoe."

The curved boundary represents the maximum color saturation. It is the result of a single wavelength of light between about 400nm to 700m. Along the bottom line of the horseshoe, the position on the line is determined by the relative magnitude of two wavelengths combined, 400nm and 700nm.

A print, or any physical, non light emitting object must completely absorb all other wavelengths of light.

Consequently, any continuous spectrum will have all of it's light, except those single wavelengths removed and thus won't produce a visible result.

As one moves from the horseshoe boundary inward, colors decrease in saturation and the maximum possible luminance a color can have increases. Luminance being the value of Y in linear space or, traditionally, L*, in CIELAB.

The theoretically possible saturation limits for colors at varying degrees of luminance are called Macadam Limits. Colors at those limits are known as "Optimal Colors." These are not actually physically possible since they require infinitely sharp and absolute frequency cutoff's as well as 100% in the passband. They are best thought of as a theoretical limit.

https://en.wikipedia.org/wiki/Gamut#/media/File:Optimal-color-solid,FL4,XYZ.gif

However, using emissive light one can produce colors anywhere within the CIEXY gamut by, for instance, using 2 lasers with wavelengths on the CIEXY boundary where the desired color lies on a line between the two boundary points. Adjusting the relative power of each laser determines where on the line the reproduced color occurs.

1

Colored chromaticity diagrams should be considered illustrative only. To @doug point, it’s not physically possible to recreate a chromaticity diagram yielding accurate color stimuli without it being self luminous and capable of being able to produce all single wavelengths between at least 380nm and 780nm (and technically from 0 to infinity)

It is common to see illustrations of the CIE diagram in print or as image files. However, filling in a CIE chromaticity diagram with colors is very misleading. Ed Breneman advocated that chromaticity diagrams not be colored because it implies a particular x,y value has a particular appearance. In fact, any point on the chromaticity diagram can be made to have any color appearance depending on the viewers state of adaptation. CIE x,y is independent of color appearance. Colored CIE diagrams should be considered to be very general representations showing where the reddish, greenish, and bluish colors fall when a viewer is in some state of normal adaptation.

  • 1
    Chromaticity diagrams describe color stimulus which is independent of state of adaptation and, yes, the state of adaptation can and does alter color perception. Often wildly. There's a lot to be said about not showing color in a CIEXY horseshoe and many don't. Especially considering it's, well, not even possible except to give people a general sense of the colors involved. – doug Sep 1 '18 at 15:05
  • @doug thanks Doug. I think we are in complete agreement – agf1997 Sep 1 '18 at 15:35
0

I do not quite understand what do you need.

...It's not something that's actually sold (in which case: why?

If you can not find something it is probably due to cost... Let me explain with my all repetitive example.

The Marker

Grab a cyan marker. Grab a newspaper and a magazine with glossy paper. Draw a line.

On the cheaper paper, you get the same process, the same ink but a dull color compared to the glossy paper, that has more coatings but costs more.

The Hexachrome

Here is another answer regarding hexachrome. It was a 6 ink printing system.

The main idea is that you could extend the gamut of the greens and oranges instead of using 4 colors, using 6. This is a 150% of the cost of using just 4 colors.

Here is a fake diagram simulating the improvement paying this extra 50% of the cost:

Do this extra colors justify the extra cost?

There are some monitors that claim to use a yellow subpixel instead of just using 3 RGB ones. RGB+Y. https://en.wikipedia.org/wiki/Quattron but it seems the backlight is not producing additional wavelengths for this subpixel to be useful, but additionally, we would need to use another file format, more space, new algorithms to compress images, etc. Costs.

Yes, we can have prints with colors out of the normal range of printers. We can use direct inks, some fluorescent inks etc. You just need to pay a bit extra.


Costs.

If you want to pay more, of course, you can, you can use some high-end monitors with 10-bit color depth and wider gamut range.

https://www.eizo.com/products/

But we are still limited. Try to work with your monitor on a sunny day on a beach... yes you could probably see the image and work on it. But it is pretty obvious that the color range of the real world is a bit bigger than your monitor.


But even if you can see more colors on your diagram, probably when you publish your work this new colors will be lost, due to cost, unless you provide everyone with a high-end monitor, or you pay extra colors to be printed. You do that in some cases; editing a blockbuster movie, a dedicated photo retouching bureau, elegant merchandise packaging, where these higher costs are justified.

0

I am an artist and I may have what you need. A few years ago I made an edition of prints of the range of my high-end inkjet printer on the CIE u'v' chromaticity diagram, showing the "real" colours (with daylight). Of course, the colours do not cover the entire diagram, they appear only where they can:

enter image description here

If you need a copy we can talk about it.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.