[Openicc] Linux CM ideology, was: meta data in test chart

[Chris Murphy]

On Jan 28, 2011, at 5:59 PM, Graeme Gill wrote:

> Chris Murphy wrote:
>> the wide gamut displays aren't clearly converging on a wide gamut aimpoint. Their marketing
>> materials make it sound like they are targeting Adobe RGB (1998) but they do this in a very
>> circumspect manner with numbers like "reproduces 95% of the Adobe RGB gamut". OK well if I have
>> two displays that reproduce 95% of the Adobe RGB gamut, they could still be rather substantially
>> different from each other.
> 
> The 95% is pretty bogus, since they "measure" it as 2D area on an xy chromaticity diagram.
> Not only is this missing a whole dimension, but the xy diagram is highly visually non-linear,
> so the area has poor practical correlation.

I do not know how the various companies making wide gamut displays are computing their volumes. At least for the NEC MutliSync PA241W I have here, ColorThink reports the "gamut volume" for it as 1,382,970 and  for Adobe RGB (1998) as 1,207,520. The red primary is certainly more chromatic for the display than ARGB, and also more chromatic but also a different hue as well as more chromatic for blue, and mostly a difference in hue for green. So while there are some colors that are encodable in ARGB but not displayable, for the most part the 3D plot backs up the gamut volume of the display being larger than ARGB. So at least for this display, 115% of Adobe RGB may very well be correct arithmetically, but doesn't tell us what areas of the color space are included or excluded

Chris Murphy