- macOS uses no sub pixel hinting since High Sierra. Instead, it's just grayscale antialiasing. To make up for the unnatural thinness that occurs when grayscale antialiasing is used, fonts are artificially bolded by a small amount.
- Linux/FreeType uses very nice-looking sub pixel hinting and maintains the clarity of fonts pretty well. The spacing between characters may not be pixel-perfect, if I remember correctly.
- Windows/ClearType snaps fonts to the pixel grid very aggressively, resulting in some amount of distortion. Many of the default Windows fonts look really good with ClearType, while others appear strange, especially at smaller sizes. In terms of technology, ClearType is the most advanced.
I’m not satisfied with your macOS glyph dilation explanations.
I don’t know the timelines involved, but my impression was that macOS’s glyph dilation has been there from the start, or at the very least waaaaay before they threw away their subpixel antialiasing. (When you wrote “sub pixel hinting”, I’m presuming you actually meant subpixel antialiasing, though feel free to correct me; but hinting and antialiasing are entirely different things, and “subpixel hinting”, which I imagine would mean hinting to subpixel boundaries (which would also seem a weird thing to do), isn’t a standard term.)
Using greyscale antialiasing doesn’t inherently make things appear thinner or thicker. The only thing that will make things appear thinner or thicker is if the antialiasing is done in the wrong colour space, typically meaning linear versus gamma-corrected.
> (When you wrote “sub pixel hinting”, I’m presuming you actually meant subpixel antialiasing, though feel free to correct me; but hinting and antialiasing are entirely different things, and “subpixel hinting”, which I imagine would mean hinting to subpixel boundaries (which would also seem a weird thing to do), isn’t a standard term.)
Yep, I think you're right about this. I can no longer edit my comment, but pretend I did a quick s/hinting/rendering/g.
> Using greyscale antialiasing doesn’t inherently make things appear thinner or thicker. The only thing that will make things appear thinner or thicker is if the antialiasing is done in the wrong colour space, typically meaning linear versus gamma-corrected.
Huh, thanks for the correction. Do you have any idea what the "Use font smoothing when available" setting actually does, given that it makes fonts thinner and more similar-looking to Windows rendering when turned off?
In the macOS User Guide, it says "Font smoothing reduces jagged edges for some fonts. When text smoothing (or “antialiasing”) is on, smaller fonts may be harder to read."
That seems misleading, though, because there is clearly some amount of antialiasing happening regardless of which option is chosen.
I think you're probably right. To be honest, everything in macOS seems to be designed with that switch on, so turning it off makes fonts in many areas look noticeably worse.
> The spacing between characters may not be pixel-perfect, if I remember correctly.
Behdad has since axed usage of hints from True/OpenType fonts. Though the rationality of "more precise positioning" is kind of irrelevant on modern HiDPI screens.
- macOS uses no sub pixel hinting since High Sierra. Instead, it's just grayscale antialiasing. To make up for the unnatural thinness that occurs when grayscale antialiasing is used, fonts are artificially bolded by a small amount.
- Linux/FreeType uses very nice-looking sub pixel hinting and maintains the clarity of fonts pretty well. The spacing between characters may not be pixel-perfect, if I remember correctly.
- Windows/ClearType snaps fonts to the pixel grid very aggressively, resulting in some amount of distortion. Many of the default Windows fonts look really good with ClearType, while others appear strange, especially at smaller sizes. In terms of technology, ClearType is the most advanced.