[arghwhat]

You really don't want to do subpixel AA anymore.

For one, subpixels aren't just lines in some order - they can have completely arbitrary geometries. A triangle, 3 vertical slats, a square split in four with a duplicate of one color, 4 different colors, subpixels that activate differently depending not just on chromaticity but also luminance (i.e., also differs with monitor brightness instead of just color), subpixels shared between other pixels (pentile) and so on.

And then there's screenshots and recordings that are completely messed up by subpixels antialiasing as the content is viewed on a different subpixel configuration or not at 1:1 physical pixels (how dare they zoom slightly in on a screenshot!).

The only type of antialiasing that works well is greyscale/alpha antialias. Subpixel antialiasing is a horrible hack that never worked well, and it will only get worse from here. The issues with QD-OLED and other new layouts underline that.

The reason we lived with it was because it was necessary hack for when screens really didn't have anywhere near enough resolution to show decently legible text at practical font sizes on VGA or Super VGA resolutions.

[alwayslikethis]

Subpixel AA is still more readable for non-HiDPI LCD screens, which are still the majority of desktop monitors sold today. It did work well enough for people to be using it for so long, and the situation with screens on desktop has mostly not changed.

[marwis]

It also works great with almost but not-quite HiDPI screens such as commonly available and cheap 4K 27" monitors. You can scale them at 150% and with ClearType it looks as good as super expensive 6K Mac screen.

In fact since cleartype effectively triples resolution I guess you get quality of 12K display?

[arghwhat]

It does not triple resolution. Subpixel rendering can only be used to smooth full pixel lines - this introduces color fringing on the sides of font glyphs, but one that can sometimes be ignored when the smoothed lines are thick enough to distract.

If you used subpixel rendering to render lines of fractional pixel thickness, it would just appear as a single-pixel line of the wrong color. The same happens if you render line thicknesses up to 1 1/3 pixels wide, but offset to not match any pixel boundary.

At the same time, subpixel antialiasing can only be used with a specific subpixel layout, in the direction sof the subpixels. For regular desktop LCD panels, this means smoothing of vertical lines only, making characters like "o" look funky and uneven.

With that in mind, a 4k panel with subpixel antialiasing does not look anything like a 6k panel with greyscale antialiasing ("super expensive mac screen" is not relevant, apart from display technology differences not related to resolution or aliasing).

[alwayslikethis]

I agree, although this isn't as noticeable as it is on a true low dpi screen. In the monitor market anything higher resolution than a 27 inch 4K tends to be ludicrously expensive, and won't be an option for most people. With Windows having pretty functional fractional scaling, I doubt anything higher than 4K will ever become mainstream, since at the distance you are using your desktop monitor, more resolution is of limited value.

[Etherlord87]

> In fact since cleartype effectively triples resolution

Only horizontally (is 4K a double or a quadruple resolution of 1080p?), and only if you don't care about color (saturation, hue).

[arghwhat]

Subpixel AA does not have significant benefits over greyscale AA on 1440p or similar displays, and it always have all the downsides. If you're rocking a large 1080p display and never share your screen (including screenshots), sure.

As the field of view taken by pixels decrease (DPI only has meaning when combined with distance to retina), anti-aliasing becomes less and less relevant. But until then, greyscale remains the lesser evil.