I am trying to compare the color gamut of a few screens but some of the screen's specs show the percentages in sRGB and some in adobe RGB. For example one screen has 72% Adobe RGB and another has 100% sRGB. How can I compare these two values when they are in different color spaces?

I know that there is some overlap between the color spaces, does this mean I can use some kind of equation to calculate the comparison at least to an approximate value?

or do I just have to decide which color space I want to use and go from there?

I just can't find a comparison chart or the way to calculate this, although I did find an occasional post that states that 91% Adobe RGB is about 89 sRGB and similar posts. How did they arrive at this conclusion?

  • Don't compare anything, ever, to NTSC. It was one of the worst colour standards of all time. It was known as Never Twice the Same Colour. – Tetsujin Nov 2 '19 at 17:31
  • @Tetsujin "Never Twice the Same Color" – scottbb Nov 2 '19 at 17:33
  • LOL - I just edited & added that as you posted. – Tetsujin Nov 2 '19 at 17:33
  • I had never seen NTSC until I first visited the states in the mid 90s. There were these, for the time, huge TVs, with the most hideous picture… & something I'd never ever seen before, a white-balance slider right on the front panel to try correct it yourself… more purple… no… more green… no… purple... – Tetsujin Nov 2 '19 at 17:35
  • ;^U^ thx deleted that part – Jay Nov 2 '19 at 17:42

You can't, just from coverage percentage numbers, because you can't tell exactly where the overlap in three-dimensional colorspace will be from a single number representing area. See How do color spaces like sRGB and Adobe RGB overlap? for details.

In practice, I would expect most monitors to give you coverage numbers for both of these color spaces. And, I would also expect that any monitor with significant Adobe RGB coverage to, for all practical purposes, entirely cover sRGB. It's only going to matter if you are trying to compare two monitors with poor color gamut to begin with, and I assume since you are asking this question you probably can just rule those right out.

  • But can I arrive at some more-or-less value that tells me - this screen has better coverage than that screen? or, there is just no way to compare two different screens if they use different color spaces and I just have to decide which color space I want to use. – Jay Nov 3 '19 at 14:07
  • @Jay you can't even tell if two monitors with the same coverage number are at all similar to each other. They may both leave out entirely different pieces of the gamut - there's no way to condense a 3D diagram into a single number. – Mark Ransom Nov 5 '19 at 19:11

It is not guaranteed, but almost all screens with 72% NTSC coverage also have around 99% sRGB coverage. Screens with 92% NTSC coverage tend to be right around 99-100% Adobe RGB coverage.

While it is true in theory that the specific 72% of NTSC colors that a specific screen can reproduce might include a significant portion of Adobe RGB colors that are outside of the range of sRGB (and thus leave out the same amount of colors within sRGB), it is also true that a screen that can produce 99% plus of sRGB and not much else will score around 72% for NTSC.

Manufacturers that design models with colors that cover significant portions of the range of colors beyond sRGB are usually going to desire to get as close to Adobe RGB or other standards beyond Adobe RGB (DCI-P3, Rec. 2020, etc).

Screens that are measured by independent testers who test for both standards almost always report 98-99% sRGB coverage for panels that score around 72% NTSC coverage. Screens that are measured at around 99% Adobe RGB coverage almost always also are tested at around 92% NTSC. So I'd say it is a pretty safe bet for around 99% sRGb coverage to be the case with monitors listed as "72% NTSC". I'd also sy you're pretty safe that monitors listed as 92% NTSC give around 99-100% Adobe RGB coverage.

Selecting a monitor tends to work best by selecting a specific color space with which you desire to output your work and then finding a panel that matches that standard well. Most good monitors are designed to get pretty close to one of the most common standards (currently it's still sRGB followed by Adobe RGB and then more exotic spaces) and not much more than that particular standard. What good would it do to have a monitor that can do around 99% of sRGB but only half of the additional colors contained in Adobe RGB? It wouldn't be any more useful than a screen that can only show 99% of sRGB and not much else.

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