The gamut solid
Hi, John,
Hi Doug,
The latter graphs are for D65 and Gamma at 2.2. Luminance is not stated, however most manufacturers issue OEM profiles based on default (max) cd/m2 settings.
The former graph (NEC 2690) is also at D65 and Gamma at 2.2, but the luminance is set at 140cd/m2 yielding a contrast ratio of 523:1 with black level of 0.28cd/m2 and DeltaE of 2.1.
No, that's not what I mean.
The actual color gamut of an output device is a three-dimensional "plot" (sometimes called the "gamut solid"). It could be done in different coordinate systems. One of those would be the CIE xyY coordinate system.
The graphs you show (and that we most often see) are two-dimensional - they show chromaticity only, showing the x and y coordinates only.
But those could be derived in several ways from the entire three-dimensional plot. For example, they could show the "cross section" of the three-dimensional solid at some value of Y (luminance) - (not the luminance setting of the monitor - a luminance value on the "Y" axis of the color solid).
Or they could be the "x-y envelope" of the three-dimensional solid - its overall outline as we would see it by observation from "high overhead" (that is, from a point of observation at a high value of Y).
The practical significance of all this is that we cannot necessarily get all chromaticities lying within the "chromaticity gamut" plot with every possible luminance. The classical example is that the highest luminance color usually available on a display is at its "white point", and we can only have that high a luminance for a color with the "white point" chromaticity. If we want come other chromaticity, it will have to be at a lower luminance.
In fact the "gamut" plots that are a triangle that are only a triangle joining the chromaticity of the three primaries of the display (the "phosphor" chromaticities, for a CRT display). We can only get all the chromaticities lying within that triangle if we are willing to limit ourselves to a maximum luminance attainable for each.
In fact, one of the reasons that some two-dimensional chromaticity gamuts look "truncated" is that they are in fact a "slice" of the three-dimensional color gamut solid at some arbitrary l(but "fairly high") luminance, where not all chromaticities within the "triangle" can be attained.
But of course to understand such a plot, we need to know at what luminance (on a relative basis, usually stated as a fraction of the luminance available at the "white point" chromaticity) it is a "slice" of the solid.
Best regards,
Doug
I wonder whether the CG210, (my monitor) would still cover that paper's gamut?,