Hector Martin

…but the ratio depends on the display, e.g. some displays have white subpixels.

DIsplay technology is irrelevant. The definition of the sRGB colorspace doesn't care how you implement it. White subpixels are a hack to get better brightness at the expense of color purity, and never help you if you're trying to cover the sRGB gamut.

I posit that any display using white subpixels and assuming subpixel independence (no weird global power limitations/interactions or whatever) that covers the sRGB gamut can also cover the sRGB gamut at identical brightness with the white subpixels always off.

ok, even though my previous statement was wrong, *that* isn’t necessarily true, since even the purest blue available is close to pure 470nm light, which is well within the range where M and L are significantly activated in addition to S; therefore…

…a display could hypothetically have a blue subpixel that’s a significantly *lower* wavelength and doesn’t activate M/L much (i.e. its ‘native’ gamut is larger), but if it only needs to cover sRGB, it can do so at a higher brightness by adding in some white

…more generally that could apply to any display whose native gamut is a superset of sRGB, I guess.

True. I will revise my statement to: a display with white subpixels will never need to activate them to more than the (linear light) sum of the maximum possible values that can be used to yield each individual sRGB primary chromaticity.

I.e. if you can use 0.05W to still get pure sRGB R,G,B primaries out of your display's native gamut, then you never need more than 0.15W overall.