Adobe RGB monitor coverage

[geotzo]

Hi all,
I have been experimenting with a few monitors lately, trying to calibrate them using i1 display pro and I am puzzled with a question:
how do their manufacturers calculate and state their Adobe RGB coverage. Some say its 95%, some 99% etc. I have used Gamutvision to compere some gamuts etc, but how can I calculate coverage of one gamut to another in terms of percentage % ? I know and I can see in Gamutvision that one gamut might be as big as Adobe RGB but it doesn't all fall into the exact same space, so I guess that means there are colours of Adobe RGB that cannot be displayed through the monitor's profile. Am I saying this right? Any thoughts would be truly helpful.
George

[Bart_van_der_Wolf]

Hi all,
I have been experimenting with a few monitors lately, trying to calibrate them using i1 display pro and I am puzzled with a question:
how do their manufacturers calculate and state their Adobe RGB coverage. Some say its 95%, some 99% etc. I have used Gamutvision to compere some gamuts etc, but how can I calculate coverage of one gamut to another in terms of percentage % ?

Hi George,

A colorspace is a coordinate system, for displays often with 3 primary colors and a range of brightnesses. That can be represented as a 3-dimensional hull that contains a range of possible colors. If one were to divide that hull up into small cubes or blobs, then one can compare the number of those that fit within the hull. That's one way how a percentage can be calculated. Different calculation methods will give somewhat different percentages.

I know and I can see in Gamutvision that one gamut might be as big as Adobe RGB but it doesn't all fall into the exact same space, so I guess that means there are colours of Adobe RGB that cannot be displayed through the monitor's profile. Am I saying this right? Any thoughts would be truly helpful.

Not all color coordinates in every colorspace amount to what we can call a color (for a human a 'color' is something a human can discriminate from other 'colors'). Some sRGB coordinates are outside the range of what most humans can discriminate as color, and a large number of very saturated coordinates of the Pro PhotoRGB space are non-colors. I believe that also most AdobeRGB coordinates can be considered to be 'colors', even though some coordinates may represent colors that are hard to distinguish from its neighboring coordinate(s).

So if a display misses some coordinates that can be encoded in the Adobe RGB colorspace, AND those coordinates represent (human distinguishable) colors, then they will be 'missing', although they will probably be mapped to another color we can see.

Also, not all images have all colors in them, so we may not be missing anything, except a few very saturated colors.

Added to this, the colorspace of the source image, will be remapped with a profile to mostly fit inside the output space's gamut. During that translation things can get 'lost' (no longer individually distinguishable) as well. The larger the destination gamut, the more nuances will be able to be encoded into individual colors/nuances.

Hope that helps a bit.

Cheers,
Bart

[geotzo]

Thanks for such a quick reply. well explained and very helpful. I was trying to find some short of easy mathematic way to calculate the Adobe RGB coverage of other specific gamuts via the tools of GamutVision software.
Thanks again

[Bart_van_der_Wolf]

Thanks for such a quick reply. well explained and very helpful. I was trying to find some short of easy mathematic way to calculate the Adobe RGB coverage of other specific gamuts via the tools of GamutVision software.

As far as I know GamutVision, which is not all that well, this page may be relevant. It shows an image of total gamut volumes of 2 profiles, which should be a simple way of approximating the percentage of ARGB that your display profile says it covers. The problem may be that you display profile covers parts that the ARGB doesn't, and vice versa. So you may actually want the intersection of both, perhaps.

Cheers,
Bart

[digitaldog]

Some say its 95%, some 99% etc. I have used Gamutvision to compere some gamuts etc, but how can I calculate coverage of one gamut to another in terms of percentage % ?

Two points (why this might be a waste of your time).
Depending on who's giving you the 'marketing spec' they may be using differing percentages:
The "Percent Area" is simply the area in CIE xy of the display gamut vs the reference gamut, with no consideration of how much of the gamuts actually overlap. This value can be > 100%.
The "Percent Coverage" is the overlapping area of the 2 gamuts expressed as a percent of the total area of the reference gamut. The maximum possible value for this is 100%.
Next, when it comes to calculating gamut, not all products are created equally. See: http://www.colorwiki.com/wiki/Color_Management_Myths_26-28#Myth_26