Wide-Gamut Displays

living with for the past several decades is, today, standardized as “Rec. 709” 1 (in the video industry) or “sRGB” 2 (in the computer industry). These systems share the same primaries. The gamut of Rec. 709/sRGB is bounded in 3-space by the triangle, depicted in Fig. 1, formed from the chromaticity coordinates of the primaries (see the sidebar, “Chronology of Display Primary Standards,” for a review of primary chromaticity – or “color space” – standards). Gamut coverage is a strong function of luminance level. Fully saturated blue, lying at the blue vertex of the triangle, can be produced up to about 7% of full white luminance, but achieving luminance higher than 7% requires adding red or green. Adding either (or both) of those reduces the color saturation of the blue, bringing the chromaticity in toward the interior of the triangle and reducing the gamut in the vicinity of blue. Similarly, fully saturated green can be produced up to a luminance of about 72%, but above that level, gamut in the green region is reduced. At white, gamut shrinks to a point. The dependence of gamut upon luminance is not easy to portray in a 2-D diagram, and display engineers tend to underestimate its importance.